15 Exposure 120 Film Back for Mamiya 645 AFD

Discussion in 'Medium Format' started by rishij, Apr 1, 2011.

  1. I've heard one can get Mamiya 645 AFD film backs modified to shoot 15 exposures per 120 roll instead of 16 exposures. This apparently helps with the film flatness problem.
    Does anyone know if one can just buy a 645 AFD film back that defaults to 15 exposures per 120 roll? Or do you have to get it modified by sending it to Mamiya Japan? Are the newer backs 15 or 16 exposures per roll?
    Just trying to step up from 35mm so any help would be greatly appreciated :)
    Thanks,
    Rishi
     
  2. Rishi,<br><br>Putting one frame less on a roll may perhaps solve frame spacing issues (i can't imagine Mamiya not being able to put 16 on a roll without problems though), but will not change how film is held flat in the magazine.
     
  3. If you look at the this thread, particularly Doug Miles' post, you'll see that setting the back to 16 exposures does potentially lead to film flatness issues on the 2nd shot you take after letting your film sit around for a while (assuming you've already advanced to the next frame). I'll just quote Doug rather than try to restate it myself:
    Yes, the film makes a tight turn over a small roller on its way to the pressure plate. If the film sits for a long time in that position, supposedly the curve may persist. The next exposure won't be affected, as that film has been sitting in position. It would be the second exposure, if the persistent curve is wound to a position in the area to be exposed. The 15-exposure option results in a longer spacing between frames, and supposedly lands the curved film beyond the frame.​
    Apparently, this way the potentially curved portion sits between frames (b/c of the larger gaps between frames, I assume that the gap fully covers the length of film over the small tight rollers).
    Another thread mentioned that the Pentax 645NII manual specifically states that you should switch to 15 exposures per roll to avoid the film flatness problem. Yet another thread that I can't find right now states that you can send in your film back to Mamiya Japan to get it changed to 15 exposures per 120 roll.
    So it appears to be a real problem... and since I'm one of those pixel peepers that really closely observes detail, & also allow film to sit in my camera for long periods of time, this issue concerns me.
    Hence my original question :)
    Thanks,
    Rishi
     
  4. Rishi,<br><br>Have you ever heard about this in any other place, from any other people?<br><br>The 'don't leave it sitting around rollers' advice is from Zeiss, who were pushing Contax's (a Zeiss owned brand name) solution to film flatness problems: a vacuum back. To be accepted as a solution, people needed to be told first there would be a problem.<br>There isn't. People have been using roll film for ages, to great effect, producing images of stunning (technical as well as artistic) quality. How could that be if there was such a Huge Problem?<br>Zeiss also told us that 220 film is flatter. To put that in perspective, you have to know that a vacuum back only works with 220 film.<br>Get the picture? ;-)<br><br>(And for anyone doubting that the learned people at Zeiss would resort to publishing nonsense, just have a look at their website, and how, for instance, it says they developed the fastest lens ever to take pictures of the Dark Side of the Moon. What dark side would that be, do they suppose? :D )<br><br>As said before, reducing the number of frames per roll does not keep film flatter. Changing the path film is fed through might, but only (!) if it has been designed exceptionally bad.<br>The not keeping it wrapped around something advice is bogus (on the 'Dark Side of the Moon' level), completely ignoring the fact that film comes wraped around a spool to begin with. If anything, giving it a curl in the film back will help make it sit flat. Not do the opposite.<br><br>So stop worrying until you actually notice anything bad. And even with you being a self-confessed pixel peeper, i bet you will not. ;-)
     
  5. it says they developed the fastest lens ever to take pictures of the Dark Side of the Moon. What dark side would that be, do they suppose? :D
    Um, I'm supposing they're talking about the side of the moon that is not visible from earth because the period of rotation of the moon = the period of revolution around the Earth? Of course, if you're orbiting the moon, you can just shoot it when there's a lot of sunlight so yeah I guess you wouldn't need a fast lens for that. Is that what you're getting at?
    I understand your point about it being wrapped around a spool, but if you look at the rollers inside some of the 120 backs, there are two rollers on one side that bend the film quite a bit. Perhaps more so than on the spool. I don't know, I'm not familiar at all with MF, but I can see an argument for film curve being introduced by bending it more than it is on the spool.
    In general, lack of evidence doesn't mean much; I'm much more inclined to believe people that say they've seen this problem & have been able to repeatedly produce it vs. people who say they've never seen it b/c the latter group may not have been looking hard enough.
    Also, if a Pentax manual literally states it... that gives the issue much more gravity.
    Cheers,
    Rishi
     
  6. Yes, there is a side of the moon we never see, but there's no side of the moon that's always dark. Talk about the Dark Side of the Moon needing their ultrafast (f/0.75) lens is as nonsensical as this bent film thing. Why! The clue is in the name: roll film. The film comes tightly rolled up around a spool!<br>And yes, tighter as it bends over rollers in a back. The rollers help to reverse the curl and keep it flat. (Something not happening in a straight path magazine, by the way.) So nothing to worry about, but on the contrary, something to be happy about.<br><br>Lack of evidence, as you put it, is evidence for a problem either going unnoticed or not exisiting. If it were a big problem, it would be hard for it to escape attention and remain unnoticed. People "not looking hard enough"? ;-) So yes, it indeed does mean quite a lot.<br>And the weight of 'evidence' suggesting that there is a problem is rather slight. Do you have that Pentax manual that says that? And if it does, why would it apply to Mamiya film backs?<br><br>Again (worded a bit differently) do not go looking for problems. If they do not present themselves to you all by themselves, they do not exist. Remember too that we're talking a bout a visual medium, i.e. 'what you don't see is not there'.<br>So stop worrying! ;-)
     
  7. Q.G.,
    I think you may be misinterpreting the issue. No one is disagreeing that changing the frame spacing or number of frames cannot change how flat the film is held, or whether a kink can get "set" into the film through inactivity for some time. What it can change, though, is the significance of where kinks end up in the film. With 15 frames per roll, the kink is "set" into the _gap_ between frames. With 16 frames per roll, the kink will be set into the _image_ area of the next frame to be exposed. That's the problem in a nutshell.
    Does anyone know if one can just buy a 645 AFD film back that defaults to 15 exposures per 120 roll? Or do you have to get it modified by sending it to Mamiya Japan? Are the newer backs 15 or 16 exposures per roll?​
    When Mamiya released the 645 AFDIII, they also released a redesigned film magazine (HM402, replacing the earlier HM401). The HM402 let the user choose whether to shoot 15 or 16 frames, for this very reason. I've never actually seen a HM402 for sale on the used market though - mainly because of the relative rarity of the 645AFDIII in comparison to the earlier 645AF, AFD, and AFDIII. You can probably buy a HM402 new, but the price will probably be stupid.
    Check out page 76 of this: http://www.mamiya.nl/client/mamiya/uploads/downloads/645afdiii_manual.pdf
    Quote: "Under certain shooting conditions, the failure of the film to straighten out may cause
    defocusing on part of the screen. When the camera has been left standing for a prolonged
    period (30 minutes or longer) after the film is wound up, the frame following the
    frame up to which the film was wound and at which the camera was left standing may be
    adversely affected by the failure of the film to straighten out. In cases like this, the effect
    can be prevented by setting the number of shooting frames to 15 frames for a 120 film or
    30 frames for a 220 film. This failure of the film to straighten out differs significantly
    depending on factors such as the type of film used and the temperature or humidity
    during shooting."
     
  8. Ray,

    No misinterpration on my side. That's the same thing Zeiss wrote when they were helping the Contax vacuum back marketing effort. Creating demand for a product that has no reason for being. "Strategic marketing" is what Zeiss called this.

    It's something we never heard of before. Which - if it is a real problem - we certainly should have, given that roll film and the backs they are run through weren't exactly new when they came up with this 'report'. Nor really heard of since.
    Or do you know where all those people go to complain about that pesky bulge left in the film for being left wrapped over a roller? (And how long has that film been wrapped over the feed spool, would you say, before it is fed in the film gate? Shorther than 30 minutes? So where did that bulge disappear to, do you suppose?)

    As for Mamiya and Pentax catering to those who fear such a problem, they do just that: cater to those who fear such a problem. Most people wonder what problem that would be, though. And perhaps they too would indeed start worrying if ever they see any of it themselves. "If", and not "when". Becaue they will not.
     
  9. Thanks Ray. Wow, $1554 on B&H. $349 just for the film insert (I guess just the film insert wouldn't help me in conjunction with one of the older film backs?).
    Man, I feel like these companies are intentionally killing film. Just sad. It's completely daunting for anyone to try to step into the MF (non-digital) field. I wanted to experiment with it stepping up from 35mm but perhaps my money/time would be better spent on a fully digital workflow.
    Q.G. you speak with a lot of authority (which you very well may have). I guess I must have more faith in people/companies though... now that I've seen the 15/16 exposure issue in both Mamiya and Pentax manuals.
    I just don't think that the curl introduced by the roller seems that implausible. I'd much rather just switch to 15 exposures/roll than take a chance with 16 where, in order to get more exposures in, the framing is kept tighter by advancing each frame less... thereby leaving the curled part within the exposure. Makes perfect sense to me. 35mm film goes through no such rollers. Which'd explain why I've never seen film flatness problems with 35mm.
    Rishi
     
  10. ... and perhaps also why Zeiss/Contax also had a vacuum back for 35 mm?<br>Maybe you just haven't looked hard enough...<br>See how it works? ;-)
     
  11. LOL Q.G. Well played... well played.
    In my limited internet searching, I've found more complaints of film flatness issues with MF than 35mm. I guess that's where my concern stemmed from.
    I've looked plenty hard & have not found varying sharpness across, say, a mountain ridge when I've nailed focus. Except near the edges at wide apertures b/c of lens defects.
    Those tightly spaced rollers just make me worry!
    Ok well one of these weekends I'll get some rolls & rent a 645 & test. Though I'll only be able to maximally give it like a 1 day waiting period (since I'll be renting) between shots to see if film curl persists...
    Interesting find with the Contax vacuum back. Did anyone ever definitively conclude whether or not it helped with 35mm?
    Rishi
     
  12. Rishi,

    You're almost there. But not quite. ;-)

    Seeing that you have "never seen film flatness problems with 35mm", why even/still ask if a proposed solution to that problem (now, what problem would that be again?) helps?
    You know the answer. You gave it yourself.

    See now how it works?
    Find something new for people to spend money on. If it would be something they need, it would have existed for aeons already. So it will be something people do not need.
    Unsaleable? Nah... People are funny. Just tell them there is a Huge Problem they need to, and can, solve with this essential new thingy. And even though they never ever felt the need, never encountered that Huge Problem, they will believe the marketing nonsense (or at the very least start wondering whether it works, even though they have "never seen [etc.]").
    Strategic Marketing. The Dark Side of the Moon.
    ;-)
     
  13. Even these guys complain about film flatness especially with 6x9:
    http://www.hevanet.com/cperez/MF_testing.html
    I think you're following this forum, Q.G.... are all these people just crazy?
    Honestly I don't think it *should* be much of a problem, like it is with scanning, b/c your back plate doesn't have to be transparent, and you push the film from the base side. Since film curls toward the emulsion side, this should effectively flatten the film.
    Which makes me wonder: how does the pressure plate exert enough force without scratching the film back?
    -Rishi
     
  14. Rishi,<br><br>When have you (!) seen (!) any film flatness problems?<br>You say you never ever have using 35 mm film, yet a single mention of Zeiss/Contax's 35 mm vacuum back is enough to make you doubt that.<br>I'll leave passing judgement about such things to you. ;-)<br><br>All a pressure plate must do is provide a flat surface for film to lie against, and gently nudge it in the correct position. Film not being made of steel, no Big Force is required at all. The force that scratches the film is the one with which it is pulled across the pressure plate. Any roughness on that plate will then be enough to cerate a scratch.<br>So if scratching film is a worry, do not use motor winders and wind on gently. Or use 120 film. ;-)
     
  15. Which makes me wonder: how does the pressure plate exert enough force without scratching the film back?​
    If we are considering 120 film here, then the back of the film is paper. Doesn't really matter if you scratch it. However, if it is a smooth surface, it isn't going to scratch anything.
    The pressure plate usually sits on a couple of raised rails which leaves just enough gap between the plate and a couple more raised rails for the film to pass through.
    I think this is a case of trying to find a solution to a problem which doesn't really exist.
     
  16. Just wanted to report back, for the sake of posterity, that when you call 'Mamiya USA', you actually get 'The Mack Group', & they had no idea what I was talking about regarding the 15 vs 16 exposures for the 120 film backs. Upon further investigation, they told me that the HM402 is the only back that allows one to select 15 vs 16 exposures per 120 roll (we already knew that!), and that there is no way to modify the HM401 to make it shoot 15 exposures per roll.
    Don't know if that's true or if they just don't know about the modification (I heard somewhere you have to send it to Mamiya Japan? How do you even contact them? Not very surprisingly, everything's in Japanese on mamiya.co.jp site).
    I'll do my own field test after getting the Phase One 645AF this weekend.
    Cheers,
    Rishi
     
  17. Q.G. & Steve,
    I find it hard to believe that all these people & these people are lying or deluded... it seems to be a real problem.
    Just got my rig today. Very disappointing if this whole thing is true. Mamiya USA said they can't modify the backs to 15 exposures/roll... in fact, they had no idea what I was talking about.
    I'll perform some tests over the next few days.
     
  18. Rishi,<br><br>Consider the many, many people who have used all those MF cameras for many, many decades without ever noticing anything wrong, and set the number of those against the few who report the problem. Makes your numbers based (dis)believe fall flat on its face. ;-)<br>Add to that that these reports only began to surface after Zeiss published their 'Contax's vacuum back will solve all of your woes' marketing thingy.<br>What would you say then?<br><br>MAC is indeed not Mamiya, but a company that hijacked the Mamiya name (and - mind bogglingly so - was allowed to do so), forcing the one and only real Mamiya to deal through them if they wanted to sell Mamiya products to U.S. users. So not really surprising.
     
  19. Yeah that's really annoying about the MAC group or whatever they're called. And I'm fairly certain that if I
    called/contacted Phase One someone there would tell me to never utter the F word ('film') again! I think it's pretty sad
    that film is really going the way of the dinosaurs & not even sticking around as an alternative format. Do any
    companies still make/support film SLRs?

    I'm loading my 1st roll of 120 film ever... Should I wind it really tight so the film is completely flat against the pressure
    plate?

    The thing that makes me believe this stuff even more is the fact that apparently Mamiya offered the modification to the
    film backs to make them shoot 15 exposures for free. No marketing ploy possible there... Sounds like honest good
    intentions to me...

    Trust me I really want to believe you Q.G. But I'm wondering if I should just return the entire system in the 2 day
    window I have & buy a 5D Mark II :)

    Rishi
     
  20. "Honest good intentions"?<br><br>Anyway, you have the gear (how else can you return it), so use it and see for yourself!<br>I hate to remind you, bit it is relevant: you never had any problems with 35 mm film, but a single mention of someone offering a solution to those problems was enough to make you doubt that. Do stop thinking like that!<br>Photography is a visual medium, what you do not see is not there, and will not suddenly become blatantly obvious the moment some company or other starts telling us we have all been blind as a bat. Some people buying into the "honest good intentions" of companies perhaps demonstrate that some of us indeed are? ;-) So run the test. See if you can find those problems yourself.<br><br>And if you decide to stick with the Mamiya (would be a good decision), but have enough doubts to still want to have the magazine fixed, would it be cruel of me to remind you of the fact that that same 'research' that 'showed' that there is that terrible film flatness problem waiting to be solved by Contax's vacuum back (or Mimiya's 15 exposure fix) also 'showed' that you need to use 220 film as well? ;-)<br><br>Anyway: loading 120 film, you should take care not to let the roll unwind and get loose, but there is no need to wind it really tight. The camera's/back's initial wind will take care of everything, take up the little slack there may be.
     
  21. As any scanning operator will attest to, bigger pieces of film are harder to hold flat... hence my lowered concerns for 35mm.
    Also, as I wind the 120 film around that first roller onto the pressure plate -- that's one heck of a bend. 35mm film undergoes no such bend before encountering the pressure plate!
    I'm just trying to find a good test chart to shoot now to verify/debunk this problem :)
    Thanks,
    Rishi
     
  22. The point about the 35 mm format was that you, though you look with a keen eye, have never seen any problems, yet mention a 'solution' to those non-existing problems once, and... ;-)<br>I.e. don't let yourself be lead by the nose by what some marketing department came up with.<br><br>Many people seem to forget that film comes wrapped around a spool, in "one heck of a bend", and stays like that for ages. One company's Strategic Marketing department lets off a mock-scientific fart (brought to you by the company who also developed an ultra fast lens to shoot the Dark Side of the Moon), and suddenly the counter bend (which - if anything - will help make the film straight again) film is put in for a brief while is the World's Biggest Problem.<br>It's not.<br><br>The sad thing about this all is not that this ploy did nothing to help sell Contax's vacuum backs, did nothing to stop Contaxt disappearing. But has managed to 'enrich' the World of Photography with a new and obviously very persistent myth that needs to be debunked over and over again. And then again. And again. And...
     
  23. Oops, I realized I didn't need to slip the film under & over the rollers, so I retract my comment about the 'heck of a bend'... it doesn't seem too bad at all!
     
  24. Q.G.: I would really encourage you to do your own testing before making claims as bold as the ones you've made in this thread.
    For the life of me I can't understand why there isn't more empirical evidence (read: pictures) showing that this is a real problem for 645 backs. Perhaps people don't like to waste film with such empirical tests.
    I waited a number of different intervals between advancing frames, from 30 seconds to 5 minutes to 1 hour to 12 hours. In the worst case (12 hours), a 4-8mm section of film in the center of the frame literally pops millimeters out from the pressure plate. In the world of micro AF adjustment for already flat CMOS sensors on new dSLRs, have you any idea how significant millimeters is?My jaw literally hit the floor when I saw this. In fact, the only film frames that are completely flat are the 1st frame & any other portion of film that hasn't sat bent around the rollers for longer than what I would guess to be 1-10 seconds. Taking a long exposure? Better throw away your next frame.
    I'm utterly speechless.
    But don't just take my word for it. I documented all this with photos, which I'll post shortly. In the meantime, let me explain to you what you apparently have to do to in order to guarantee exposures on flat film:
    If you just loaded your film:
    • 1st shot: fine
    • 2nd shot: crap (unless you loaded ur film & began shooting in under 30 seconds, which is impossible), so fire off 2 shots.
    • Now your next shot (#4) will be fine, but #5 will be crap so you'll have to fire off 2 shots (#5 + #6). #7 will be fine, but #8 will not, so you'll have to fire off 2 shots (#8 + #9). And so on & so forth...

    Not only is that a waste of film, but it's complicated as all heck! Imagine trying to auto-exposure bracket with that algorithm above. I like to think i'm fairly intelligent, but that'd be like rocket science to me out in the field while i'm trying to focus on photography, not on the inadequacies of my equipment.

    Let me recap. If you follow the protocol I outlined above for your 16 exposure 120 roll, here's what you'll get:

    #1: good
    #2: crap
    #3: what #2 shoulda been
    #4: good
    #5: crap
    #6: what #5 shoulda been
    #7: good
    #8: crap
    #9: what #8 shoulda been
    #10: good
    #11: crap
    #12: what #11 shoulda been
    #13: good
    #14: crap
    #15: what #14 shoulda been
    #16: good

    And all that will only be the case if you fire the following shots in rapid succession:

    • 2+3
    • 5+6
    • 8+9
    • 11+12
    • 14+15

    The defect in the film was so easy to see I documented all this with photos that I'm piecing together. Next, I will shoot actual test charts & scan them on an Imacon to assess the severity of this problem & hopefully convince people once & for all & "debunk" this debate by showing that the problem does actually exist.
    Good grief. My entire system is going back asap given that I can return it. I can see why people swear by the Mamiya 6x7 rangefinders now as they treat the film just like 35mm cameras: no tight obnoxious bending around rollers. And hence it makes sense that they hold the film flat. Sorry, Q.G., but your argument of 'the film is already wound around the rollers' falls apart b/c the film is not wound with anywhere near as much tension, nor does it undergo literally 90º bends under tension, on the film roll. So the film roll doesn't introduce flatness issues; the rollers in 645 backs do.
    And while we're on this topic, since the bent film is in the middle of the ~42mm (height) frame of the film, in order to avoid this problem the film would have to be advanced an extra ~21mm after each frame. So let's do a backhand calculation to see how we could fix this problem:
    Total length of usable 120 film: 16 exposures x ~42mm = 672mm
    Now if the film should be advanced an extra 21mm for each frame, that means that each frame now takes up 42mm+21mm = 63mm
    672mm/63mm = 10.67 total frames... or 10 frames rounded down. That's a rough calculation, since I didn't account for the first or last frames & don't feel like fully thinking out this problem right now.
    So I don't even understand how changing the # of exposures to 15 fixes the problem. Maybe if they changed the # of exposures to 10 or 11...
    And I don't even know how to contact Mamiya to talk to someone about this. Truly, it's almost a crime that a film back like this could've been released & allowed to circulate amongst consumers & 'professionals' for decades.
    Here is the 1st frame of film after loading... notice it's relatively flat (not entirely so; look at the curvature on the left side):
    [​IMG]
    Here's the 2nd frame, after sitting overnight. Notice it looks like someone literally picked up the Velvia film & bent it in half:
    [​IMG]
    Now do you believe me? If not, just wait for some high-resolution scans of actual material shot on film this bent out of shape (pun intended). Additionally, I took many other shots of what the film looks like when it's been sitting varying amounts of time. Don't have time to post it right now but will do so shortly.
    IMHO, this is the kinda stuff that is directly responsible for the death of film. And, sadly, all avoidable with more intelligent R&D to begin with. I don't know whether to laugh or cry.
    -Rishi
     
  25. Actually, in my calculations I forgot to factor in the spacing between frames that already exists for 16 exposure 120 film. So maybe that's why I'm only getting 10.67 frames per roll if you want to fix this film curl problem.
    Does anyone know off-hand the distance between frames for 120 rolls shot with 16 exposures (in mm)? I can update my calculation then.
    Thanks,
    Rishi
     
  26. Rishi,

    I have done my empirical testing continuously for more decades than i care to remind myself of. So have millions with me.

    I do believe your results. We can see what we can see.
    What should make you think a bit is your "So I don't even understand how changing the # of exposures to 15 fixes the problem. Maybe if they changed the # of exposures to 10 or 11..."
    Why do people who believe there is a problem say it can be fixed that way?
    According to your test and calculations, it wouldn't. If i would rephrase that as "it would not make a difference", we're already at where we should be at. ;-)
     
  27. we're already at where we should be at. ;-)​
    NO, we're absolutely not where we should be at. Advance each frame an extra 21mm, and then we'll be at where we should be at.
    Also, with your experience, surely you can quote me the mm distance in between 120 frames for 16 exposures/frame. Then I can redo my calculation. Maybe it does come out to 15.
    Please please please if you have some 120 film lying around uncut, measure the distance between frames & let me know so I can redo the calculation. Else we'll have to wait days for my own test!
    Thanks,
    Rishi
     
  28. Here's the bend in the film (RVP 50) after sitting for only 1 hour on the rollers:
    [​IMG]
    I mean... really... I wish this were a joke. It's not!
    Mamiya? Phase One? Hello? Ansel Adams is rolling over in his grave...
    -Rishi
     
  29. And here's Frame #4, which spent just 5 minutes on the rollers:
    [​IMG]
    5 minutes, folks. Which sometimes amounts to the time I need to meter a complex scene (ok, a bit of hyperbole there, but you get the idea).
    -Rishi
     
  30. Rishi,<br><br>Have to run, so only a short reply. The distance between frames on 120 film is not set to that degree of precision. It all depends on the transport mechanism, how loose the film is on the roll, the thickness of the paper, the thickness of the film, and such. So it can and will vary from film type to film type, from back to back, from brand to brand (of back, and of film) from roll to roll, from the first frame to the last.<br><br>I will suggest you run another series of tests though. And in that test you should actually exposing the film in the regular fashion and examine the resulting images.<br>Reflections are great to detect minute deviations from the plane (you can measure the curvature/circumference of the earth with rather astonishing ease and accuracy using light reflecting off a bath of mercury). But would you not want to know how bad this would affect the images, rather than how bad it can look when looking at the film?
     
  31. "And in that test you should actually exposing the film in the regular fashion and examine the resulting images."​
    Q.G., that is on the books. It's exactly what I intend to do. But even without doing those tests, let me put things in perspective again. The film bend jumps millimeters off the pressure plate. Let me now quote an article that addresses the need for micro-adjustment for autofocus & talks about the levels of tolerance needed to ensure sharp focus from a lens onto a high resolution sensor:
    How small of a variation? One of his sources said as little as 20 microns (0.02mm or 0.0008 inches) is sufficient to cause side to side variation. You can only detect that amount of variation with laboratory grade laser equipment, I’m told. Medical-grade machine parts (used in arthroscopes, etc.) are expected to have tolerances of about 50 microns, (3) and it would seem unlikely that a camera lens mount would be made more than twice as accurately as a medical arthroscope. In other words, with a top quality wide-angle lens on a high resolution sensor, we can perceive a 20 micron difference, but the manufacturer probably can’t make the part more accurately than +/- 50 microns at a reasonable cost.What concerns me is the authority with which you spoke without ever indicating that you performed empirical tests yourself.
    -"This Lens is Soft" & Other Facts, original article here.​
    Microns. So we're talking about the film bend introducing a misalignment of focus (a couple millimeters) that is 1-2 orders of magnitude more than the levels of misalignment between lens & digital sensor that result in perceivable loss of sharpness.
    So, I'll do the test... but do I even have to? Furthermore, let me quote some personal communication with Bill from www.getDPI.com forums:
    "I fully understand your problem. Although I haven't shot film recently, the problem you document was quite bad, particularly with the Hasselblad and Mamiya which both bend the film around the rollers at more than 90 degrees. The only solution was to shoot at f11!

    I moved to the Rollei 6008 system where the magazine is quite a lot longer because the film does not get bent at all. It just comes straight off the roll into the film gate with no bending. It was a big improvement."
    -Bill Caulfeild-Browne​
    What concerns me is the authority with which you spoke earlier, dismissing these 'rumors' that needed to be 'debunked'. Made me comfortable enough to buy this entire system, thinking it may serve me better than a 5D Mark II. I'm not blaming you at all; I'm a grown man who has to make his own decisions... & I can't say this was entirely not-worthwhile... I think we all learned something here.
    But, I have to ask: have you performed the simple test I performed above? Have you shot high frequency material & scanned at high-resolution & verified yourself there's no loss in resolution due to these hideous bends in the film?
    -Rishi
     
  32. Rishi,<br><br>What still concerns me is how you summarily dismiss many hundreds of thousands of people using MF for just about 100 years without noticing anything bad, until Zeiss said to look at our films and how they bulge.<br>So (as you did concerning that 35 mm vacuum back thingy) you swallow that hook line and sinker, and look and see your film bulge, and show great concern about that, without (!) even testing what all those many hundreds of thousands could have told you.<br><br>And yes, you are far better served using MF film (even rather crappy MF film cameras) than that Canon. We don't even have to consider film flatness to know that.<br><br>Now, could i interest you in the millions of excellent large format photos that have been made since photography was invented, and then tell you to have a look at how sheet film sags in the holder? I think i know what would capture your attention - the beautiful pictures or the sagging film - then too ;-)
     
  33. Again, that test is on the books & I'll post my film scans hopefully within the week. So please be patient.
    In the meantime, I'm arguing that there's no way it can't make a difference because the numbers (mm vs microns) speak for themselves. Unless you want to argue that Velvia film isn't high enough resolution next to a modern DSLR for this to matter... which I certainly hope you don't think.
    Once again, one carefully done, repeatable, reproducible negative result is all that is needed to 'debunk' this problem. Sure many people may not have seen it because:
    • They didn't look for it/didn't scan at high enough resolutions
    • Shot the roll in rapid succession
    • Shot at high apertures, like the f/11 that Bill mentions
    • Shot shallow DOF portraits where it's hard to tell what's supposed to be in focus vs. not
    I could quote you many reasons why many people don't see it. Doesn't mean the problem doesn't exist. A guy on these very forums shot newspapers on a wall and saw the same problem (here's his post): a section in the middle of the frame was completely out of focus across the frame (left to right). That's exactly what the predicted outcome is for my findings. Bill confirms the problem in his findings. That's enough evidence for me to shy the heck away from this format, but, like I said, I'll confirm with actual shots.
    But regardless, there's enough evidence to show that the design flaw exists. And worse, it's easily rectifiable... but not by me or any end-user. And now impossible, it would seem, given the drop of film support by these companies. What a tragedy!
    And what will convince you that it is, in fact, a real world problem? A clearly visible loss in sharpness could indicate a 2x drop in resolution, or more. What would people say if Canon released the 5D Mark III & followed it up with a statement "The middle 10% of your image may drop from 28MP to 14MP resolution or less every now and then if you shoot at wide apertures". Imagine that!
    Again, I'll attempt the test, though it's rather hard to quantify the exact loss in resolution since you need to have a chart that's already at the limiting resolution of the film at the center of the frame. Or a chart with increasing density of lines from left to right... but the resolution captured might then depend on lens aberrations. I'll have to think a little harder about this...
    -Rishi
    P.S. I would be willing to bet you that the film sag with LF can cause a loss in resolution, & people either shoot at small apertures or otherwise justify that 'it's ok because the enlargement factor from large format is so much less'. Which defeats the point that if there's a sag you're not doing the film's resolution justice. Whether or not that matters to you is a different story.
     
  34. Let me quote Andrew Schank from his photo.net post here:
    Many people have experienced a lack of sharpness in some of their 120 images because of this and don't correctly attribute it to film curl. It often just looks like you slightly missed the focus. On a resolutiom chart with my Rollei,I can take several images without changing anything on the camera except advancing the film, and there can be large differences in the lines per mm resolved. It is less noticeable at f11 & 16 than at f4 and f5.6.​
    There you go. How many people do these sorts of tests with resolution test charts? It's not exactly easy nor the most fun thing to do. If you're just going to say 'it doesn't matter in the real world' I will still point out to you that regardless you would be losing resolving capability of your film at these heavily curled spots, & that places a severe limitation on your imaging format especially in the face of advancements in digital sensor technology. For example, sometimes I will shoot a faraway landscape at f/4 with my 70-200 f/4 L IS so that I can shoot handheld in available light. It would really not be cool if I had to accept the fact that I will experience softness due to the f/4 aperture... that would be a severe limitation.
    -Rishi
     
  35. Rishi,<br><br>Run the test yourself. You're jumping from reasons why people (you do know the number of people you are talking about?) might have missed it to reports of that they haven't, from there to that they have because noone shoots test charts to who knows what's next.<br><br>This entire thing is like people looking for a nice small boat to have some fun on the water with, reading a report that you can't actually sail a boat on water, because water is soft, and the boat will sink in it, and if it doesn't, the water is always moving and rippling (at best) and that's a huge problem. They will go and look at water, see how easy it is to submerge their hands when they put then in the water, proving that there is indeed very little resistance and anything you pt on it will indeed sink. And lo and behold, still water is indeed very, very rare. So there! It's proven you can't sail a boat! Next someone tells them people have been doing so for thousands of years, and their reply is to ask whether that someone tried it himself by doing the same thing they have, and how anyone could arrive at a different conclusion. And besides, there are reports of boats that sunk. So... <br>;-)<br><br>It is not (!) a problem, except in the minds of people who indeed believe that that airplane they see in the sky can't possibly fly, because everyone knows that [etc. etc. etc.].
     
  36. Oh c'mon Q.G. That metaphorical comparison is just silly & you know it.
    I provided you with evidence that shifts of 20-50 microns between the lens & sensor can cause softness on modern high-end DSLRs (otherwise why would AF microadjustment help?). A 5D Mark II can, at best, resolve ~156 lines/mm with its sensor given its pixel count (simple math). Mauro Franic & I showed that Velvia 50 + lens can resolve 150 lines/mm for a 1:20 contrast chart. Fujifilm themselves measured their film & claim that it resolves 160 lines/mm for 1:1.6 contrast (without lens). So we were right in the ballpark for film + lens combination. Hence the resolving power for the Velvia is at least as good as, if not better, than that of the 5D Mark II.
    Therefore, you cannot argue that the same 20-50 microns (or more) shift will cause softness on a 5D Mark II but not on Velvia. And I showed you film popping millimeters out from the pressure plate.
    For your ship/water analogy, the guy claiming that water is soft would have to show you a boat that sinks that is indeed constructed similar to a boat that floats, at which point you, in disbelief, would try to find a flaw in the sinking boat. In your analogy, looking for that flaw in that sinking boat is equivalent to finding a reason why Velvia film that pops that much does not cause a loss in resolution (I had to spend a while thinking about your analogy). Well, the only way that is possible is if Velvia resolves less than a 5D Mark II sensor. Which is just not true according to Fujifilm.
    QED.
    -Rishi
    P.S. It'd be pretty funny if I proved myself wrong... but as a scientist, I have to always be open to the possibility :) You'll hear back from me hopefully by the end of the week with real world tests & scans.
     
  37. And for anyone who thinks that leaving the frame of film that was previously on the rollers on the pressure plate for a while straightens out the film, think again...
    Here's frame #2 which sat on the rollers for 12 hours, and then sat on the pressure plate for 1 hour (after advancement to shooting position):
    [​IMG]
    Hardly any change, in my opinion. Not surprising, since the pressure plate hardly exerts any real pressure in my estimation...
    Rishi
     
  38. As I've been (accurately) quoted by Rishi, I'll pitch in.
    I have used 4 by 5 inch cameras and yes, film flatness is an issue, though sheet film never was bent. It still bulged a bit in the middle of the holder. The saving grace is that the 4 by 5 lenses are not very fast and in any case, especially for landscape shooters, are used considerably stopped down.

    With Hasselblads (in the 1980s anyway) I found the problem quite acute. So acute in fact that I could see no point in using F2.8 or worse, f2. (I had a 2000 FC ). But as a landscaper, I generally shot for max dof so it wasn't a major issue for me.

    And Hassy's had the problem of backs mating properly with the camera body, too, which didn't help. I moved to the Rollei 6008 partly because its magazines did not require any bend in the film and I was able to shoot at larger apertures with confidence.

    I still have hundreds of Kodachrome 120 shots from that era. That film had very high resolution and was very unforgiving of any focus errors, but rarely did I have a problem with the Rollei shots.
    Bill
     
  39. Rishi,
    As a scientist, you should get things straight, not mix things up.
    The depth of film and that of a digital sensor differ considerably. So the focussing accuracy required for either does not transfer to the other. It's more difficult to get an image in focus on digital sensors.
    So though i didn't even want to, i certainly can argue that "the same 20-50 microns (or more) shift will cause softness on a 5D Mark II but not on Velvia", and be absolutely right too. But that's irrelevant.

    Here's (another) question for you: do you think you (or an AF system) can set the lens to film distance (i.e. focus) within microns of what it is supposed to be?

    And have you measured the "milimeters" the film bulges?

    The simile is a bit silly, yes. Of course it is. But really not inaccurate.
    The guys who told us that film bulging is a terrible problem should (like you) not just pontificate about the fact that they can show that film bulges, but at least also show that that is a problem. They haven't, just as you still haven't tried to find the problem. Bill at least has reported results. I don't share his experience (and yes, i also use the f/2 lens, at f/2), and i am sure very many with me don't. But that at least is a report not just of a 'cause' for possible problems, but of a result of a cause.
    So again, stop worrying about causes, and start looking for effects.
    I will again remind you of the 35 mm vacuum back episode: you are sure you have never seen a problem, but a single mention of a 'solution' and you're convinced there must be?
     
  40. I will again remind you of the 35 mm vacuum back episode: you are sure you have never seen a problem, but a single mention of a 'solution' and you're convinced there must be?​
    Who said I was convinced of a problem with 35mm film? I'm absolutely not convinced, because 35mm doesn't make any sharp angles around any rollers!
    And have you measured the "milimeters" the film bulges?​
    Yes. Sorry next time I'll place the ruler in the image when I take shot of the film bulge.
    Here's (another) question for you: do you think you (or an AF system) can set the lens to film distance (i.e. focus) within microns of what it is supposed to be?​
    Instead of asking so many questions, why don't you answer one?
    It's more difficult to get an image in focus on digital sensors.​
    Why? Light that falls on the sensor plane is focused by microlenses, making the effective focal plane pretty thin. Film also has a very thin focal plane, though technically a different one for each color emulsion. I have no idea how the two compare, but can you give me some rationale for this claim?
    -Rishi
    P.S. I'm tired of repeating myself, but, I have a job. It's been a day since I identified this problem, so give me a break. The results are coming. Meanwhile, the theoretical side of this discussion is interesting to me. But if you're going to make bold claims, it'd really help the rest of the community if you backed them (e.g. 'It's more difficult to get an image in focus on digital sensors').
     
  41. Here's (another) question for you: do you think you (or an AF system) can set the lens to film distance (i.e. focus) within microns of what it is supposed to be?​
    To answer your question: yes... within a tolerance of 20-50 microns according to that article. Or presumably at least elements can be moved within the lens (these aren't single element designs) such that the effective simple lens to film distance is changed on the order of hundreds to tens of microns.
    Let me put it this way: when I rotate the manual focus ring on my 50mm lens, I can move the barrel in sub-millimeter steps. My rough estimate holding a ruler close to the front barrel: I can move the ring about 10 discrete times or more as the barrel extends from 0mm to 1mm. Those are 100 micron steps. Any one of those steps can completely throw off the focus of an object 10ft.
    A very unscientific test, but, it'd indicate that the answer to your question is yes.
    Since you asked the question in a rather authoritative tone, I assume you have the answer?
    -Rishi
     
  42. Also, FYI, the AF motor in the Rebel T2i can well outresolve the movements I can make to the manual focus ring with my hand, thereby nailing focus even better than my hands can (although I can do just as well with my bare hands with a lot of trial & error).
    Gotta love technology. I think this is one of the reasons we see defects more easily today is b/c digital technology has allowed us to make critical evaluations with relative ease.
    -Rishi
     
  43. Rishi- Not to get involved in the film flatness debate (never had an issue on my Hassy or Yashicamat, but did on cheaper 120 cameras, so I can see both sides here), but I will comment on the 'harder to focus with digital' bit.
    Film is three-dimensional, even if it is perfectly flat. It is just barely three-dimensional, but it is. Colour film especially has three or four layers of emulsion, each sensitive to a different colour. This means if your focus is off by a few microns, or if you have a small amount of chromatic aberration from a cheap UV filter or a poorly coated lens (or a close-up filter on a lens that doesn't like them), often each layer of emulsion will see what it wants to see, and disregard the 'wrong' bits. This may lead to one or two layers of emulsion that are out of focus, but another that isn't, which makes the image look sharper.
    Digital sensors, even those like the Foveon with layers, are really still two-dimensional. The first layer is covered in microlenses, which shunts the image off to where it has to go. That means that focus (and colour alignment) needs to be perfect on that first layer, as the microlenses effectively act as a single layer of emulsion.
    This is a VERY miniscule difference mind you, and in practice does not make a huge difference. I only see a difference when using 1.4 lenses, and even that can be chalked up to the worse viewfinder on most digital cameras. It does result in a quantifiable difference in CA though.
     
  44. Rishi,<br><br>This is getting off topic, but still a fun debate: it's not about whether a lens can move to any position (it of course can, from stop to stop it moves through any position in between), but whether you are able to hit the desired position within that accuracy of 50 microns either way. That involves a bit more than just being able to move a lens. First, for instance, you have to be able to determine what that desired position would be.<br><br>Anyway, here is some more 'disconcerting' information to ponder. ;-)<br>You have a Pentax, my data are relevant to Hasselblads, but i doubt that there is much of a difference. The body length of these cameras is adjusted within a tolerance of plus or minus 30 microns. The film position within the magazine within a tolerance of plus or minus 50 microns. There are similar tolerances on focussing screen position and mirror angle.<br>And yet these are held in rather high esteem for being precision machines (and not undeservedly so), capable of producing images of excellent quality.<br>How could that be? ;-)<br><br>And further: i never said you were conviced there is a problem with 35 mm film. I have pointed out to you that you were absolutely convinced there wasn't one, and that the mere mention of someone marketing a 'solution' was enough to sway you and make you doubt what was your knowledge and conviction. I did that (repeatedly) not to suggest that you think there is a problem, but to demonstrate how these reports produced by Strategic Marketing Departments produce the desired effect with the greatest of ease. People will believe absolutely anything if told in the right way. Beware of that. ;-)
     
  45. Q.G.:
    I have pointed out to you that you were absolutely convinced there wasn't one, and that the mere mention of someone marketing a 'solution' was enough to sway you and make you doubt what was your knowledge and conviction.​
    No, what made me 'doubt' was my scientific mindset which is trained to always question.
    And yet these are held in rather high esteem for being precision machines (and not undeservedly so), capable of producing images of excellent quality.​
    Again, maybe because it wasn't as easy to observe as it is now with digital sensors (that provide quicker feedback & therefore allow tests to be carried out with less hassle) & technology such as Live View with 10x magnification. Now it is extremely easy to critically judge focus/sharpness errors by comparing images side-by-side on a monitor or layering them in Photoshop & switching between layers. This sort of critical evaluation just wasn't available to the average consumer decades ago. You may argue at this point that such critical evaluation is only for academic purposes, and I might agree with that. But since I have a scientific mindset & wish to evaluate a system's potential before I invest in it (especially in the face of options like MF digital or 24MP full-frame dSLRs), I do not find this sort of debate or critical evaluation unreasonable.
    That involves a bit more than just being able to move a lens. First, for instance, you have to be able to determine what that desired position would be.​
    FYI when I reported that I could move the lens element hundreds of microns (maybe less) in my earlier post, and even nail focus but not as easily as the camera nails focus, I was assaying this by Live View at 10x magnification. That's how I determined what was in perfect focus or not.
    Also, I have the Mamiya 645AFD III, not the Pentax.
     
  46. Zack, thanks for your answer! That makes sense... I'd started to put two and two together last night when I figured that the plane of focus is really thin for digital SLRs b/c of their microlenses, while the plane of focus on film varies due to the emulsion layers... but I didn't figure it would make much of a difference. For film, anyway, wouldn't you want to nail the green-sensitive layer, given that that's what humans are most sensitive to?
    I can perhaps buy that the film may be more forgiving, but I do know that with one of my telephoto lenses (L-series, tack sharp for most of the field) that renders the left ~15% of the image slightly soft at f/4 does so on both my 5D & my 35mm film shot in my EOS-3. In other words, though I haven't done extensive side-by-side testing to quantify the difference, in real world shots I can see the falloff of sharpness on the horizon with shots taken on 35mm Velvia as well as a 5D with that same lens. Neither seems more forgiving than the other. I assume this is due to a misaligned element that leads to that part of the image missing the focal plane, b/c the glass on this lens is otherwise perfect & it's supposed to literally be Canon's sharpest lens.
    -Rishi
     
  47. Rishi,<br><br>The point that still doesn't come ac ross, it appears, is that film technology has been tried and tested over and over again, by countless people, both sloppy and uncritical, and the analy precise, over an exceedingly (compared to how long it should take for anything bad to show itself) long time. If anything was up with film, we would know it.<br>Not that film is perfect. But if there was that problem Zeiss wanted us to buy that Contax and vacuum back for, we would have known. We really would.<br><br>You're "easy to observe" point is something you should think about for a while. Remember that we're dealing with a visual medium. If something marring image quality hides itself particularly well, it, by doing so, lessens itself as a problem. If noone ever notices, it's not there.<br>The fact that problems are so much more easy to detect in digital capture says a lot about digital capture. And that's it. If you really believe that now, people compare images more than ever, you will have to think again. If you think that computer screens (of all things!) makes comparing easier or even more accurate, you are on the wrong track entirely.<br>So critical evaluation was more available back when digital technology did not exist. Less so now. What has changed is that nowadays anyone can post scans and digitally captured images on the web, and claim that we see something looking at them that may or not be there. (And don't get me started about the nonsensical "comparisons" that indeed abound on the web. ;-) )<br><br>I too do not find critical evaluation unreasonable. What i do find unreasonable is unreasonable "evaluation". Things like ignoring the already mentioned ongoing test, by countless of people, and the results of that, asking if i (or anyone) has tested film yet... (What do you think? ;-) )<br><br>Anyhow, let's wait and see what your test results show.<br><br>A few miscellaneous notes:<br><br>Micro-lens arrays on sensors are not the problem. Sensors are shallow.<br><br>Softness in images can be caused by quite a few things besides film flatness and focussing error. If a lens' performance drops at infinity when set to a closer distance, it will be mostly the effect of focussing, i.e. the lens is not focussed to infinity so the horizon will be soft (what else can it be? Something people who use hyperfocal distances to 'focus' should know, but - proving your point about not looking closely enough - given the ongoing popularity of the 'technique' many apparently don't. Proving also my point that many people rather believe what they read somewhere than what they (should) know and understand ;-) ). It can also be just a matter of lens design, and the resulting behaviour, worsening the effect of disfocussing. Why do you think it would be a misaligned element, i.e. a manufacturing/quality control error?<br><br>P.S.<br>My aplogies for mixing up the Pentax with the Mamiya. The point however remains the same. What do you make of it?
     
  48. If anything was up with film, we would know it.​
    You continue to deny the 'countless' (if I may use that word) people who do claim that they see real-world softness due to film flatness problems. Just search photo.net. Seriously, arguing with you is pointless if you pick & choose which results to believe. You're trying to prove something doesn't exist for which there is evidence that it does exist.
    If you really believe that now, people compare images more than ever, you will have to think again. If you think that computer screens (of all things!) makes comparing easier or even more accurate, you are on the wrong track entirely.
    So critical evaluation was more available back when digital technology did not exist. Less so now.​
    We're gonna just have to agree to disagree. Yes it is much easier now to test the sharpness of lenses with a digital camera using live-view to ensure focus & then by doing side-by-side or layered comparisons in Photoshop than it was to use a huge magnifying loupe or a light microscope to judge sharpness of one film frame vs. the next (that you have to switch between) that you may or may not have properly focused/exposed, etc. Even comparing prints side-by-side is not as easy and is more prone to human error than switching between layered images in Photoshop. To suggest anything else is ludicrous. You may argue that practically speaking, we should just look at the print. But for academic purposes in evaluating a system, the accurate and objective method is the more preferred.
    Now, judging of film resolution is still hard in today's age, b/c scanners add another layer/variable. Probably a light microscope is still the best way. But even that is not as objective as a stellar/optimal scan on a high-resolution scanner that is then run through mathematical analysis software such as Imatest.
    Micro-lens arrays on sensors are not the problem. Sensors are shallow.​
    Sensors are shallow compared to the depth of film? Again, if you make statements like this, please back them up with resources stating actual numbers. What Zack was saying was that the micro-lens array makes the effective focal plane of a digital sensor quite shallow... perhaps shallower than the effective focal plane of the film given its different emulsion layers. Your statement is once again a bold claim without any support.
    Why do you think it would be a misaligned element, i.e. a manufacturing/quality control error?​
    Um, you're suggesting the very vague 'quality control error' whereas I'm suggesting a basis for that quality control error. Please try & make your point clearer, in more rigorous scientific terms.
    -Rishi
     
  49. I got some numbers if anyone's interested:
    CCD pixel depth can be on the order of 5 microns.
    Film base is ~100 microns for 120 film, & in Fuji's diagrams it appears that the color emulsion layers together are on the order of thickness of the film base... so maybe we're talking about 50 microns depth per color layer?
    So I think those numbers give Q.G.'s statement 'digital sensors are shallower than film' some credence (you're welcome Q.G.).
    But it's hard to assess what this means in the real world in terms of lens sharpness tolerance (or focus tolerance). In film, it's not like light rays falling within the a certain pixel pitch all get binned to the same pixel. If focus is off, the light ray may travel further or less through the emulsion & therefore expose a grain at a different location (in the X-Y plane of the film). So technically that should introduce loss of sharpness... but if you invoke the theory that an area of film has to be large enough to resolve thousands of levels of tones before it can be thought of as a 'resolving element' (like a pixel), then, yes you can kind of treat a certain square area of film as a 'bin' that will average whatever photons strike the emulsion within that 'bin'.
    But this is all conjecture at this point & I don't even know if this process is well understood. After all, weren't theories of how film really works put forth after people developed film itself?
    Rishi
     
  50. Dude. Rishi. (Dudette?) You're about three steps from suggesting that we're all, like, molecules in some giant's fingernail, man. I actually think I'd need to go back to college and smoke some of that 'green stuff' to understand what you just said.
    Lemme' sum up what others have said, and hopefully it will help. I tried to read that last post, but I honestly couldn't understand it. I don't mean to be offensive, but it's 10:00 here and I've had a loooong day. I hope my summation clears things up.
    Anything with an aperture will have a depth of field. Even enlarging and projecting lenses have a depth of field, although the variations are so slight that it doesn't usually matter to most people. The image that leaves the back of the lens also has a depth of field. Since film thickness varies (both base and emulsion), camera and lens designers generally design their gear with a little tolerance, or 'wiggle room' so that a loose lens mount, or a different thickness of film, or a loose film plate, won't drastically impact the negative quality. Since the receptive part of the digital sensor is so much thinner than film, exact alignment becomes more important; it's basically like trying to park the same car in a much smaller parking space. It still fits, but there's not as much margin for error anymore. This doesn't generally have a huge effect on focus, but colour alignment is even pickier, so you might see an issue there.
    To rephrase the vacuum back statement: film flatness issues due to film that's been bent around a roller probably isn't a huge issue, or else more people would produce a fix for it. A good analogy for this is the audio/cable company Monster, which produces a 'power cleaner.' If you live in a building with poorly or long-ago wired electricty, the claim is that it can affect the performance of a stereo, recording device, hot lights, or anything else that requires a constant voltage or is suseptible to 60-cycle hum. If Monster was still the only company that made such a device, we could assume that the claim was bunk. Since many other companies make such a device, and since a lot of audio components build the circuitry into their components now, we can assume Monster's claim about 'dirty power' is valid.
    Since Nikon, Canon, Pentax, Hasselblad, Leica, etc. haven't gotten on board with vacuum backs, we can assume the arguement is bunk.
     
  51. It's 'dude' :)
    And since Pentax & Mamiya redesigned their 645 film backs, one could argue that the argument is not bunk. Perhaps the vacuum back is a bit too much though.
    I'm receiving a re-designed film back from Mamiya USA (full details on that later), so I will put both to the test & post my results here so we can settle this debate. I realize I'm not going to definitively prove my point (even to myself) until I've done the real-world test, so, cheers for now!
    Thanks to all for the interesting discussion,
    Rishi
     
  52. No, no, Rishi.<br>You're still ignoring marketing. Your focus is completely on the one thingy, blocking out all the relevant other bits that make up the complete picture.<br>When did Pentax and Mamiya come up with their solution? Mamiya, for instance, has been in the 6x4.5 camera making business for more than half a century. Other companies have been making these things for much longer still. Never did they offer a solution to that 'problem'. Until, that is, Contax tried to carry their vacuum back thingy over to their 6x4.5 camera, and Zeiss conveniently provided a 'rationale' to do so (you know, that company that also knew they needed a superfast lens to take pictures of the far side of the Moon).<br>What's more, people have been using these machines for ages without ever noticing anything bad. Yes, you then like to think they haven't looked. But really...<br><br>At the time when all these 6x4.5 machines appeared, the market was beginning to shift to the Digido, and film was beginning to be perceived as the realm of the discerning 35 mm format photographer, who really knew what was better (not hard at that time, with 1.6 MP cameras being marketed as of professional quality, and as good as we would ever want it to be - with the bulk of snappers and professionals alike actually believing that.)<br>So while 35 mm format film eating machines were beginning to be replaced with terrible digital things, the 35 mm photographers 'in the know' moved towards he realm where the people who had known about the format disadvantage of subminiature format all along have been busy, but without wanting to give up the convenience. So things like the Pentax appeared: medium format with all the comforts of 35 mm format. Mamiya, who had been making 6x4.5 cameras for ages, responded. So did Contax, and (eventually) Hasselblad.<br>So tapping into the concerns of those discerning photographers who knew that the proposed 2 MP (the number kept creeping up, but the promise that it was better than everything we had known before remained the same) 'solutions' were complete nonsense, the industry found and co-created a new market. A succesfull one too. While there was little money to be made in the MF market (never had been - compared to 35 mm format, the medium format market never amounted to much), this was a thing that held a lot of promise. The result was overcrowding: every MF manufacturer jumped in and wanted a share. And that's when Zeiss/Contax decided to play the film flatness card. To gain market share. A marketing instrument.<br>And you have to keep in mind that this market was one in which people moved who had had little or no previous experience with roll film, so did not know from personal experience that this flatness thing was a crock (people who had been using roll film for ages did know that: like you and your 35 mm film, they had never ever seen the problem this was supposed to be a solution to.) And it stuck: it succeeded in sowing the seeds of doubt. Just like the mere mention of Contax's 35 mm format vacuum back made you doubt your personal observation that there was no problem with 35 mm film that needed such a solution.<br>And once this thing had surfaced and registered in the minds of some (and no sooner), apparently a couple of other companies - competing for dear life to retain a share in the quickly dwindling market (the MP numbers kept creeping up, and film - all film - was losing to digital rapidly) thought they could make use of it, by at least teelling Joe 'Spending' Public that Contax wasn't the only option for anyone who had those Contax created concerns.<br><br>So "since Pentax & Mamiya redesigned their 645 film backs", considering the context and moment in time, "one could argue that" that factoid itself adds weight to the notion, if not proves it, that it is all nothing but marketing. And one could not just argue that, it is indeed that. ;-)
     
  53. What's more, people have been using these machines for ages without ever noticing anything bad. Yes, you then like to think they haven't looked.​
    You continue to ignore the reports of the many who have seen real-world issues with film flatness in medium format systems. You'd make one heck of a corrupt scientist, selecting data that fits your hypothesis & discarding data that goes against it.
    Just like the mere mention of Contax's 35 mm format vacuum back made you doubt your personal observation that there was no problem with 35 mm film that needed such a solution.​
    For the last time, understand that my 'doubt' comes from the fact that I'm a scientist trained to question any belief when new evidence is presented to counter said belief. Clearly, you're not of a scientific mindset.
    Therefore, I refuse to continue arguing with you.
    I actually already have my real-world results, & am off to scan the frames of film to present the results to the community here. All I can say for now, Q.G., is: prepare to wish you could go back & delete all of your posts in this thread. Unless, of course, you're a troll, in which case you will have accomplished your mission of wasting my time in arguing with you.
    Now, if you'll be so kind, answer me these 3 simple questions:
    1. Have you ever used a Mamiya 645 system?
    2. If so, have you ever empirically tested whether or not a film flatness issue exists?
    3. If not, why do you think you can speak with the authoritative tone you speak with in this thread?
    Because I can tell you that now, after looking at my developed film, you're completely, egregiously, 100% wrong.
    Hopefully will be back tonight or tomorrow with the scanned frames of film showing how horrendous this problem actually is. I'm appalled, & the guy over at Panda Labs here in Seattle looked at the exposed frames of film with a bend & said something along the lines of: 'I have no idea what I'm supposed to focus on here; there's nothing in focus!'
    What's truly sad is the ridiculous price Mamiya USA is charging me for a supposedly 'fixed' film back. They should perform repairs on film backs that had a design flaw from the onset for free. Anyway, it's in the mail, so after I receive it I'll again test it to see if it solves the problem. And then maybe take issue with Mamiya Japan for not supporting their own products.
    -Rishi
     
  54. No Rishi, i do not continue to ignore anything. I do know about MF quite well, and am able to read the conclusions of the 'critical review' provided by a century old collective history of roll film use.<br><br>Yes, there are problems. (Need i mention, for instance, the word "Holga"?) Given the vast number of roll film using systems, would your scientifically keen mind suspect anything else? But still you rather assume that the mere existance of problems means it is a general issue, even though the general lack of evidence for anything of the sort?<br><br>And regarding your (frankly, rather insulting) questions:<br>
    1. Yes. Quite a bit, in fact.<br>2. Yes. (You have asked this before and still choose to ignore the answer that i, and a vast number of other people, have.)<br>3. Must i assume that your scientific method consist of lulling yourself into believing that anyone who doesn't agree with your hunches, unfounded beliefs and fears doesn't know what he or she is talking about, and that only a few gifted scientists like you have managed to see something, that has shown itself to you to be such an enormous problem that there's even 'nothing to focus on'? That, or he/she must be a troll?<br><br>Let me tell you - with authority, yes ;-) - that anyone who manages to produce shots that provide nothing to focus on should test something else first before looking for and talking about film flatness issues.<br>Do you really think that all those people who have used MF before are blind as a bat, and therefore rather stupid to use (and prefer) MF over subminiature format?<br><br>But no worries: just get a Contax 645, the Contax Vacuum Back, and 220 film.<br>Next thing you will be providing evidence that will make me (or so you'll surely think) eat the words i uttered about the Dark Side of the Moon...<br>;-)<br><br>Meanwhile the blind-as-a-bat people using Mamiyas, Bronicas, Hasselblads, Pentaxes, Rolleis, etc. will, i fear, happily go on using their Mamiyas, Bronicas etcetera. What can we do about that...? ;-)
     
  55. 1. Yes. Quite a bit, in fact.
    2. Yes. (You have asked this before and still choose to ignore the answer that i, and a vast number of other people, have.)​
    Ok. Where are your results? I've provided you with hard evidence, pictures, & more pictures of scans forthcoming... i.e. no 'unfounded beliefs & fears', at least, not any longer after my empirical testing. I'm not ignoring your answer; I'm telling you that your simple words aren't enough. In science, we present data to convince someone of a point.
    Do you really think that all those people who have used MF before are blind as a bat, and therefore rather stupid to use (and prefer) MF over subminiature format?​
    No, I'm not talking about all medium format users, I'm talking specifically about the Mamiya 645 AFD system employing the HM-401 unmodified film back. Are you being purposefully obtuse?
     
  56. Rishi,<br><br>You keep asking for the sake of asking. You do know what the results are.<br> The results are such that they kept those many hundreds of thousands [etcetera, etcetera, etcetera].<br><br>And as for your continuing claim that you are in fact doing science here. We could test and discuss this, but you and i know what the outcome will be. ;-)<br><br>No, you're not talking about all medium format users. But you are building a case on things that, if real, should affect all medium format users.<br>Yes, you have a Mamiya, so are concerned about that. So you quite rightly tested that back. Tested for those effects that are inherent to the use of roll film in cameras that bend the film (and even discounting the bend roll film comes in, that includes just about any MF camera, with only very, very few exceptions).<br>The result of your 'scientific test' should make you scratch your head. "Nothing in focus". Really? How could that be?<br><br>And finally: again, resorting to insults does not help to swing your case in your favour.
     
  57. No, you're not talking about all medium format users. But you are building a case on things that, if real, should affect all medium format users.​
    You realize that your two sentences contradict one another, right? No I'm building no such case. There are many ways to design rollers for a film back. Some bend the film at two 90º angles. Another can put one 45º bend. Others, like rangefinders, don't bend the film around rollers at all! Then you can change the amount of the spacing between frames. All these permutations can conceivably affect one back's performance vs. another. Again, are you being purposefully obtuse with your ignorant statement about my potential finding affecting all medium format users? The only statement I'm making is this: Mamiya's 645 AFD 120/220 back is inherently flawed. I want people to know this, & I want Mamiya to do something about it other than try to sell the redesigned HM-402 back for $1600. I mean, $1600 for a little black box of gears, a motor, & some rudimentary electronics? Are you kidding me?
    The result of your 'scientific test' should make you scratch your head. "Nothing in focus". Really? How could that be?​
    You love taking stuff out of context, don't you? Obviously something's in focus. It was a hyperbolic statement aimed to prove a point. The top & bottom of the frame are perfectly in focus. The entire center region, however, is completely blurred. Much like others have reported with this very system right here on photo.net. You know, the claims you continue to ignore. You will see the hard evidence yourself when I post the scans here. FYI my testing was highly methodical. Focus was locked & not changed in between shots. Mirror Lock-Up with timer was used to ensure no camera shake.
    And finally: again, resorting to insults does not help to swing your case in your favour.​
    I didn't insult you. I just told you you were wrong. And that your continued arguing in the face of hard evidence made me question whether or not you were trolling here. It's a pretty reasonable conjecture, if you ask me, given that based on my methodical testing, you're just misinforming any reader of this thread.
    In fact, after I write up an article for this issue (I've been given the go-ahead by chief admin Josh Root), I'd suggest the moderators just delete most of the posts in this thread since people not having the patience to read it all the way through are just going to be confused by this stupid argument you & I are having in the face of the hard evidence I've presented & will continue to present.
    -Rishi
     
  58. There is no contradiction, Rishi.
    And yes, you are building your case on what Zeiss told us all some years ago, i.e. that film takes on any bend it is put in. Something we, blind-as-a-bat, obtuse and unscientific photographers never noticed before.
    You have tested a (your) back, once, and found that your test proves Zeiss right. Many hundreds of thousands have tested their backs, day in day out, for many, many decades, and never seen any evidence.
    But that doesn't count for anything, right? Because these people indeed are blind-as-a-bat, obtuse and unscientific. Now who's ignoring evidence, yet again?
    So do write that article. And yes, do ask the moderators to delete all posts on Photo.net that do not agree with you.
    Very scientific. ;-)

    Meanwhile i, and the many hundreds of thousands, will be using our cameras that put film in bends, like we have done for ages before Zeiss released their 'scientific' evidence into the rumour circuit, and still fail to notice anything bad.
    Blessed are the ignorant, right? ;-)
     
  59. "Many hundreds of thousands have tested their backs, day in day out, for many, many decades, and never seen any evidence."​
    Yeah? So why can't I find ONE objective comparison where someone loaded the film, let it sit there for a day, then fired off two shots of a flat field (e.g. a horizon) at a large aperture, then scanned in & demonstrated there are no problems? If hundreds of thousands of people have supposedly done this, with objective methods like using resolution test charts (let's be serious; I'm doubtful that there are even THOUSANDS of people who print out & shoot resolution test charts), then maybe we could find at least ONE objective test that showed this ISN'T a problem.
    Meanwhile, right here on photo.net someone posted images showing there IS a problem. Much like I'm about to do. It's too bad that guy's images are no longer available b/c of his server deactivation.
    Or, for that matter, why haven't YOU even explained your methodology for the tests you claim you yourself have carried out?
    Maybe you always shoot at small apertures. Maybe Joe always shoots three dimensional objects like faces. Maybe Bob shoots entire rolls within a few minutes. In all these scenarios, or any combination thereof, the photographer might not notice the problem. That's why I'm doing an objective test. So don't even talk to me about your tests until you tell us about the methodology you used to recreate the conditions for the problem to occur & then show us the results that they did not occur.
    Furthermore, I never suggested to delete posts countering my findings (although one might question the value of posts countering my findings with only emotional arguments & no hard evidence); I suggested photo.net delete all our bickering posts (including mine), since I maintain that our entire back-and-forth bickering is useless at best & distracting at worse in the face of the main point: which is that I have clearly reproduced the problem that Contax, Zeiss, Mamiya & Pentax claim exist by following their very methodology for recreating the conditions under which one might encounter said problem.
    And yeah imagine that: a top-notch optics company like Zeiss finding a problem that the average end user might not have seen! Unbelievable!
    "Blessed are the ignorant."​
    You said it bro. Amen.
    P.S. Just to whet your appetite, I go from 600 lines/picture height to 200 lines/picture height going from frame 1 to frame with the 645 back (in the center of te frame). Do you realize that that makes the 2nd frame of MF film lower in overall resolution than 35mm?
     
  60. Just to make sure you understand that I'm trying to objectively test something that an average user may not see under many shooting conditions, I'm going to repeat what I said above:
    Maybe you always shoot at small apertures. Maybe Joe always shoots three dimensional objects like faces. Maybe Bob shoots entire rolls within a few minutes. In all these scenarios, or any combination thereof, the photographer might not notice the problem. That's why I'm doing an objective test.​
    But that doesn't mean that the problem I'm trying to report on is irrelevant to real-world results. No imaging system, let alone a supposedly 'professional' imaging system, should even on occasion drop to providing 11% (1/3 x 1/3 = 1/9, if you do the math for dropping from 600 lines/picture height to 200 lines/picture height in either X or Y direction) or less of its stated resolution unless it's due to user error.
    P.S. I'm saying 'per picture height' right now b/c I haven't had a chance to measure, in mm, using a micrometer, the exact height of the resolution test chart on my frame of film. The point, for now, remains the same. Using a light microscope I can resolve down to 6-7 on the ISO 12233 chart I shot on frame 1, but only down to 2 on the 2nd frame (in the center). That means that say I was initially resolving 150 lines/mm; on the 2nd frame, I'd be resolving 50 lines/mm or less. Stated differently, that's an 89% drop in overall resolution of the format.
     
  61. Rishi,<br><br>You keep ignoring the obvious by asking for objective tests. As if the obvious would not be so, once you could let a test loose on it.<br>But instead of trying to look for a test that will 'unprove' the obvious under the guise of that being good science, it would be far better to be really scientific about it and recognize that we do not need a test to, say, prove that water is wet. We have known that for millions of years, out of common (both as in shared and as in everyday) experience. Calling for an objective test does nothing to that, cannot change anything. All it does is show that you do not agree.<br>One objective, and scientific (it's all about numbers, right?) test is the one i keep referring you to, the one that made it obvious that roll film works pretty well, without the 'problems' Zeiss wanted to sell us a solution to: the hundreds of thousands of people who have exposed many millions frames on roll film that should have shown the result (you have given a measure for the magnitude: would it go unnoticed, you think?), without setting off alarm bells ringing.<br>But you discount that on the basis of your test (the outcome of which i do not dispute) and the seeds of doubt sown by Zeiss, and keep calling for a comparison that proves, well..., that 'water is wet'. ;-)
     
  62. One objective, and scientific (it's all about numbers, right?) test is the one i keep referring you to, the one that made it obvious that roll film works pretty well, without the 'problems' Zeiss wanted to sell us a solution to: the hundreds of thousands of people who have exposed many millions frames on roll film that should have shown the result​
    That's not a scientific test. It's not done in a controlled environment with variables vs. controls. Clearly you don't understand the scientific method.
    Your understanding of the philosophy of knowledge could also use some work. Remember that thousands believed the world was flat until one very well done, controlled & reproducible experiment was able to falsify that view. Note, controlled AND reproducible. Not one or the other, but both.
    Finally, what exactly is your point? If you don't dispute my finding, then you agree that this can be a potential problem. If I test this with say 2 more 645 AFD back I can rent locally & show the same result, that'd buttress my argument even more. And then what would you say? You'd go back to your pointless argument that thousands haven't seen it & so it isn't a real world problem. Even though I've already pointed out that there are many reasons why someone may not see it in casual shooting.
    But that doesn't take away from my main point. Say I had my roll sitting around for a few days & then I go to catch a magnificent sunset & frames 12, 13, & 14 (I bracket +/- 2/3 stop with Velvia) captured the moment of epic lighting & had the perfect composition. Now frame #13 (-2/3 stop) nailed the exposure, yet has its center completely out of focus. You think that's acceptable?
    And since my preliminary tests showed that the bend can occur within 5 minutes, say your next epic shot was taken 10 minutes later. Again, you nailed the -2/3 stop exposure. Again, since it was the 2nd frame, it's out of focus in the center.
    You think that's acceptable?
    What's your point, if you believe my findings?
     
  63. To be clear, my point is to inform others of this potential problem so that when they evaluate possible medium format systems, they can make a more informed decisions.
    My point is also this: film is already hard enough to justify shooting in today's digital age. Spending top dollar on a larger format system for film is even harder to justify. Harder to justify still with problems such as this. I just Mamiya to take some responsibility. Especially b/c who else can fix this problem for all the 645 backs circulating in the used market?
    Incidentally, I just talked to Phase One Tech Support, who told me that the tolerance of the position of their CCD plane must be 10 microns on their high resolution sensors to ensure focus accuracy (i.e. that the distance of the light path to the phase-detection system = distance of light path to sensor plane). It still amuses me that you somehow think that film floating 1000 microns above its supposed plane of accurate focus won't cause a perceivable loss in sharpness.
    -Rishi
     
  64. After researching more medium format backs/inserts today, I have the following to add:
    Pentax 67 system treats the film like 35mm; i.e. no rollers to bend the film around, so this system likely does not suffer from a film flatness issue.
    Hasselblad 6x6 backs seem to have only one roller putting a constant bend around the film (rather than the two sharp 90º bends that my 645 AFD insert puts into the film); additionally, there's a side rail right above the pressure plate that would flatten any bulge in the center of the film, at least one side of the frame. So, likely the Hasselblad system would suffer from the issues I've pointed out less.
    Do you see my point, Q.G.? My finding does not implicate all medium format systems; for now, it only implicates that the Mamiya 645 film insert system is severely flawed. This means your hundreds of thousands figure for the # of people that have successfully shot images without seeing this problem should be lowered to a smaller sample that includes only people who used the 645 AF series.
    That's of course not to say that other systems don't have this problem. The Mamiya 645 Pro insert looked like it might also share this problem, though it was slightly different in design so I'd have to verify it.
    I'll shoot more film types & with more backs I can rent locally just to put this problem to bed. Will also report results with the new back, which arrives from Mamiya tomorrow.
    Rishi
     
  65. Rishi,<br><br>I do see your point, and it is flawed.<br>It assumes that only one particular degree of bend can cause problems, ignores that the reverse curve design, if anything, actually helps keep film flatter, contains a spurious argument based on the notion that two rollers create a worse bend than just one, and is based on the false assumption that only a few cameras of the many used have this troublesome film path design.<br>;-)
     
  66. I do see your point, and it is flawed​
    It's flawed, in your opinion, because you don't understand the scientific method.
    It assumes that only one particular degree of bend can cause problems​
    No, you assume that that's what I'm trying to say from my data. In fact, I say nothing of the sort. Many things can cause problems, but in the scientific method, you break things down to simple components you can analyze. My data & analysis show the problem & I've also offered a solution: advance the film more (at the cost of film) so that the bend exists between frames.
    contains a spurious argument based on the notion that two rollers create a worse bend than just one​
    In science, that's called a hypothesis based on observed data. It's testable, and not spurious until you've tested & shown it isn't so. So what gives you the gall to call it spurious, I don't know. Perhaps the same gall that's allowed you to so self-righteously mislead me & any other reader of this thread that this film flatness problem doesn't exist.
    Also, with a little common sense & creative thinking one-who-is-not-you could deduce that one small roller near the pressure plate could introduce a smaller (though potentially equally as bad or worse) bend that would then sit very close to the frame of the exposure. But then with a little extra spacing between frames, one could make that smaller, tight yet offensive, bend not matter because it would sit between frames. Amazing what a little creative thinking gets you isn't it? Not that I expect you to even comprehend what I just wrote.
    and is based on the false assumption that only a few cameras of the many used have this troublesome film path design.​
    The only one making assumptions here is you. Who said this? Not me. I only tried to hammer home the point that my data only applies to the film back I tested. In fact, I was being humble & trying to say you can't generalize to all medium format systems with my findings. Something else we're taught to do in science...
    My scans are done & about to be posted so you'll have plenty of opportunity to eat your own words. Seriously, I'm done arguing with you. The results will speak for themselves. As far as I'm concerned, you'd be that guy, back when evidence was presented that the world was round, screaming 'the world (or film, as it were) is flat because we've all known it to be so since the dawn of mankind!'
    To which I would say:
    http://www.thinkgeek.com/images/products/zoom/despair-poster-idiocy.jpg
    -Rishi
     
  67. Rishi,

    One assumption:
    Hasselblad 6x6 backs seem to have only one roller putting a constant bend around the film (rather than the two sharp 90º bends that my 645 AFD insert puts into the film)​
    As if it matters. Does it?
    You certainly have concluded it does, based on no less than "with a little common sense & creative thinking". :D

    One further flaw (also an assumption, by the way) is the two bends thing. Same quote.
    What makes you think it makes a difference, and why? And (perhaps more importantly) where did you get the idea that the film path in a Mamiya 645 AF D is different from that in a Hasselblad? It's not.

    What's next? Oh, yes: your point that it would only affect the Mamiya you have, so the weight of evidence provided by the many hundreds of thousands people using similar cameras with similar film, thus should have experienced similar problems could be ignored, even if we are to assume that the thing happens because (as Zeiss told us) film assumes a lasting bulge when put around a roller, so any other system that puts film around a roller should also show the problem.
    Could be, could be. But then we would need to know why the problem exists in the first place, if it is not because of the reason which dictates that any other camera with similar film path should also show the problem. Is it Mamiya 645 AF D magic? ;-)

    Your solution: advance the film so that the bulge would fall in between two frames. Have you thought about that? How any frames would you then get on a roll again?
    I'll explain: it would mean that you need to move the bulge created before the film enters the gate to the other side of the gate, i.e. you would get one frame, than a blank of at least the same size of the frame, than another frame, etc. Some solution, that ;-)
    Besides, it confirms film's behavioru when bend around a roller as the cause of the problem, i.e. makes it impossible to ignore the experience of people who use camera in which film is bend around a roller. You know: those 'hundreds of thousands' again. So would require an explanation why noone noticed anything until Zeiss told us we should? Blind as a bat, 'ey? ;-)

    And all that to show that your "finding does not implicate all medium format systems", i.e. imply that the film bulge problem is not something that is film related, still ignoring (another flaw) that the majority of the systems used by the most critical MF users do put film in a bend that would throw focus of completely once the frame is advanced. If you want to build a case, try to explain why these systems are different in a way that would make a difference.

    More? There is more, but really, i can't be bothered today. Sorry!

    But finally: as for understanding the scientific method, you're again being presumptuous. Part of my day job is to teach people to recognize good and bad science. And i am not bad at it. Not bad at all. ;-)
    So as a parting shot for today, one other recurring spurious argument you seem to be married to: using the word "science" does not make what you apply it to science. So do not be so concerned so much about whether someone understands science, and concentrate on the matter in hand itself instead.
    And just so that this is clear: i'm not accusing you of doing bad science here. You're not doing science, are not being scientific, at all. Just use that claim as a not very good debating 'trick'. ;-)
     
  68. You certainly have concluded it does, based on no less than "with a little common sense & creative thinking". :D
    You really don't understand the difference between a conclusion & a hypothesis, do you?
    where did you get the idea that the film path in a Mamiya 645 AF D is different from that in a Hasselblad? It's not.​
    Different sizes of benders placed at different positions along the path will bend the film to differing degrees & will also place the bend at different points along the film; the latter being important b/c it can be designed to be placed between frames. Really. Why do I have to explain this to you? Can't you exercise some independent thought? How can you be so presumptuous as to say that there's no difference in the film path from one back to another?
    Oh, yes: your point that it would only affect the Mamiya you have​
    No, no, no NO NO! For the last time quit bending my words. I was only stating that I'm not going to presumptuous enough to say that my problem extends to all backs. It might, but it might not. I really can't say! And I don't have the time or money to test every back out there; I'm getting a Ph.D in virology for crying out loud. And why would I want to anyway? I'm simply reporting on a system that I decided to invest in which is clearly flawed. Why? In the hopes that someone else in my position may either make a more informed decision on the 645 AFD system. Or show that the problem can be fixed (with the new back, which I'm about to test), in which case I'll be helping steer someone in the right direction if they decided to pursue this system.
    Your solution: advance the film so that the bulge would fall in between two frames. Have you thought about that? How any frames would you then get on a roll again?
    I'll explain: it would mean that you need to move the bulge created before the film enters the gate to the other side of the gate, i.e. you would get one frame, than a blank of at least the same size of the frame, than another frame, etc. Some solution, that ;-)​
    Sure, that's one way. A really stupid way. Think a little harder. Or just read my last post a little more carefully where I outlined a better way to do it that might still get you 15 exposures per roll (indeed, I believe that's what Mamiya did with the redesigned back). But like I said when I wrote my design idea in my last post: I didn't expect you to comprehend it.
    And all that to show that your "finding does not implicate all medium format systems", i.e. imply that the film bulge problem is not something that is film related,​
    Imply that the film bulge problem is not something film related? Are you utterly insane or just being obtuse again? Here's the film bulge put into the film by the rollers when you pull the film out of the insert:
    [​IMG]
    Of course it's film related. And yeah, this problem would affect all MF systems that use rollers. But whether or not that manifests in your final images depends on the degree to which this occurs (which depends on # of rollers & size of rollers) & how you intelligently (or not) design the spacing between frames. Do I have to spell it out for you any further or could you possibly use your imagination & try to understand how different designs might address this problem to varying degrees of success?
    You're not doing science, are not being scientific, at all.​
    Justify that statement. I'm testing a system with variables & controls. You're just sitting there in your comfortable chair denying results & not doing any tests yourself. So to hear this statement from you is laughable, really.
    -Rishi
     
  69. Here's the design of the film insert in the re-designed HM-401:
    [​IMG]
    With one less roller, it's possible that the length of film experiencing a bend is reduced. Of course, this is easily verifiable by anyone willing to just do the experiment, rather than, say, just sitting around busting someone else's...
    -Rishi
     
  70. And, for the community at large here, I want to be clear:
    --Q.G.: You're denying this problem exists. Correct?
    If so that's fine with me. I just want you to make one clear, succinct point relevant to this thread.
     
  71. Still have yet to see an image that shows the problem, i have search quite a bit and i cant find a posted image that shows a problem due to film flatness.
     
  72. Rishi,<br><br>This to end this nonsense as far as i am concernded, only, as per request, one succinct point relevant to this thread: if you really think that people believed the earth was flat (whether or not it was until science proved it not to be), you are definitely not the one who should be casting dispersions about people's 'scientific' stature.<br>Do you get the point? And how this is indeed very relevant to this thread? Perhaps not.<br><br>Now, how does it feel to have joined the ranks of the (almost, in your case) graduated people who talk about things like the dark side of the Moon? ;-)
     
  73. Fair enough David, & I agree with you. I'm appalled that I can't find talk about the film flatness problem, but no images clearly showing the problem (well, some existed but have been deleted off the server as there's just an image placeholder where the image should be).
    So let me rectify that problem. In the interest of time, I haven't written up a detail comparison yet, but here are screenshots in my 'Compare' module in Lightroom clearly showing the problem:

    Note, the picture on the left is the 1st frame & the picture on the right is the 2nd frame (the one left sitting on the rollers). Note that focus was NOT CHANGED between frames, & shots were done with mirror lock-up & then a 4 second timer to allow for vibrations to be dampened. Scans done on a Flextight X1 @3200 PPI (an inadequate resolution... *sigh*).
    Center crop (for exact portion of image enlarged, note the 'navigator' pane in the upper left):
    [​IMG]
    Top Center:
    [​IMG]
    Bottom Left:
    [​IMG]
    Note how it's mostly just the center that's out of focus, due to the bend/bulge existing in the center of the frame that I shot a picture of earlier (here it is for you again):
    [​IMG]
    Right-click on any image to download & view at 100%.
    Why doesn't everyone with this back notice this problem? Maybe you fire through shots rapidly without letting the film sit. Alternatively, if you're shooting 3-dimensional objects, you might just chalk off that one frame as you having misfocused or the object (like a person's face) having a different depth at that point or moving in & out of the plane of focus since he/she/it is not a stationary object. Does that make this design flaw something you should just ignore & deal with? No, IMHO. The imaging system itself shouldn't be the source of variable error; we as humans make enough mistakes.
    For anyone interesting in calculating the actual resolutions from the center crop above, just take the highest number you can clearly resolve (MTF ~5-10%), multiply it by 100, then divide by 11.34mm (which is the picture height in the frame, measured with a micrometer).
    Here are my back-of-the-hand calculations:
    1. Unbent frame: 7 x 100 / 11.34mm = 62 lines/mm
    2. Bent frame: 2.75 x 100 / 11.34mm = 24 lines/mm
    So frame 2 is resolving about 39% of frame 1. In other words, 35mm film would've done better than that 2nd frame. (Limiting resolution numbers picked off of chart indicated in bold).
    If you're curious about why I'm getting such low resolving powers for Provia 400x (for 1:1.6 contrast, one should be getting 110 lines/mm without factoring in the loss of resolution due to the lens), it's because the focus was clearly off to begin with. This is indicated by the fact that at f/8 & f/11, the resolving power increases, which it shouldn't for this lens b/c I've tested this lens (the 105-210 AF ULD) on a digital sensor that showed that resolving power at f/4.5 is approximately equal to resolving power at f/11 and actually starts dropping off after f/8 (on a 5D Mark II anyway). Perhaps the path to the phase-detection system doesn't equal the path to the film plane... but really that's for another thread/day.
    Anyway, there you have a nice story. Everything falls into place beautifully. And by that I mean horribly. Contax, Pentax, Zeiss, Mamiya had a point. Imagine that! Certainly easier to believe than what the conspiracy-minded Q.G. de Bakker would have you believe: that all these companies were involved in a mass campaign to delude the public. Right...
    Allow me to quote Steve Hendrix of Capture Integration: "the issue of film bending affects all 645 cameras. It is something that photographers for decades have been aware of and have continued to shoot with these cameras regardless."
    Actually, Q.G., since you keep telling me to take into consideration the observation of others... in my estimate, from all the people I've talked to, you & the people who don't believe in film flatness problems in MF are in the minority.
    As for your laughable statement:
    if you really think that people believed the earth was flat, you are definitely not the one who should be casting dispersions about people's 'scientific' stature.​
    Do you think the people who wrote the bible knew the earth was a sphere? Do you think they also knew that light can behave as a wave & diffracts? Or that neurons can regenerate? Get my point here? What's yours? That knowledge is stagnant & unmalleable? That we knew everything from day one? My bringing up the world being flat/round metaphor was to prove a point: that you're denying evidence clearly presented to you without even doing the experiments to back up your disapproval.
    -Rishi
     
  74. Can I suggest the obvious?
    Shoot the whole roll at one time.
     
  75. Did you just take 4 minutes to set up your composition & meter that critical scene for a perfect exposure on Velvia after loading your film? Uh oh, better not AEB & skip that 2nd frame!

    Did you just take a 4 minute exposure? Remember to skip that 2nd frame!

    Did the lighting just get boring for 5 minutes? Make sure you skip the film frame after you take this shot!

    (Slide) film is hard enough to shoot already without such inane constraints.

    Also, as I will hopefully show later, the problem outlined here is a solvable one by a hardware re-design. Which is
    exactly what Mamiya did, albeit a surprisingly silent one...

    Rishi
     
  76. If you were addressing me.
    I have a Rollei. My film is flat.

    Until I hang it up to dry, then I get an edge to edge curl.
    Do you have any suggestions to solve that?
     
  77. Richard, why is that a problem? What do you wish to do with the film once it's processed?
     
  78. Put it in a negative carrier and enlarge it.

    A couple weeks in a print file sleeve in my binder flattens it.
    But I want to print sooner of course.
     
  79. Richard,
    I don't do any optical enlarging/darkroom work, so I'm afraid I don't have any suggestions.
    I can tell you though that for scanning, 35mm anyway, I have built my own holder for my Minolta Dimage Scan Elite 5400, incorporating my own film flattening techniques using some special material. One can also use anti-newton glass if the light source is diffuse enough. This is why anti-newton glass plays well with the LS-9000.
    Out of curiosity, why don't you use a digital workflow incorporating scanning?
    -Rishi
     
  80. Meaning, Richard, a proper scanner + sharpening yields much better results than optical enlargement. Read: http://www.normankoren.com/Tutorials/MTF2.html
    Of course, if only a scanner at a reasonable price/weight point existed that got all the resolution & dynamic range off of Velvia...
     
  81. hello all
    I have read all you answers. Here are my findings with these cameras:
    1. hasselblad a120-aeroshooting: every third or whatever amount of images were unsharp-unsharp zones. hasselblad told the slit had to be covered with tape. beforehand i exchanged the elx with contax rts III due to that problem... crazy wrong decision.
    2. tomiyama 612-press-mount. we had to improve film-tension to get better flatness. was not easy since some parts could not be removed.
    3. anthony sansone told me one should load film in the last moment before shooting.
    i will use 70mm-film on rb67/70mm back with vaccum. on rz67 first. there is an adapter to use it on 4x5.
     
  82. Wanted to update this thread for the sake of posterity:
    I did get a modified HM401 film back from Ramesh at the MAC Group. It had one roller removed, and put lots of extra spacing in between film frames. It solved the film flatness issue. However, it had 2 problems:
    1. Due to the increased spacing, I only got 13-14 exposures per 120 roll
    2. There was a constant current draw of ~27mA even when the body was off. Compare that to 0mA draw with an unmodified HM401
    3. There was a constant current draw of 150mA when the body was one. Compare that to 100mA draw when on with an unmodified HM401
    So, I got that replaced with yet another modified HM401. It does not have the battery/current drain issue; however, it puts less spacing in between frames (and is *actually* a 15 exposure film back... rather than a 13-14 exposure back due to the vastly increased spacing between frames). I was worried that with the less spacing I'd still see the bend introduced into the film within the exposure area... turns out it seems fine. I let film sit in there for days, then advanced one frame; the film looked flat. Perhaps just the removal of that one extra roller takes care of all the bending problems.
    If you want to try & get a modified HM401 back to deal with the film flatness problem, you need to contact Ramesh at the MAC Group (RameshP@MACgroupUS.com according to http://www.mac-on-campus.com/AboutMACOnCampus/MACGroupContacts.aspx). I would try calling 914.347.3300 (according to their website: http://www.macgroupus.com/).

    Ask for Ramesh, and ask about the modified HM401 film back that has one of its rollers removed and puts extra space in between frames. Then, when you get it, test it out! Load your film, then let it sit for a day or so. Then, take an exposure so that the film advances. Pop off the film back, remove the safety plate, and see if there's a bend within the exposure area. Hopefully there isn't!

    Furthermore, if you know how to, test the current draw :)

    This is the setup for testing it... should be obvious to anyone somewhat electronics savvy:
    [​IMG]

    It can be a bit difficult connecting the leads inside the battery compartment of the AFD body... but it's doable. Just don't short anything :) The film back should really have no draw when the body is off.

    Good luck to anyone going this route. Without that modified back, I would never invest in the Mamiya 645AFD system for film shooting.
     

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