15 Exposure 120 Film Back for Mamiya 645 AFD

rishij · April 21, 2011

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

q.g._de_bakker · April 22, 2011

No, no, Rishi. 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. 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). 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... 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.) 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. 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. 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. 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. 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. ;-)

rishij · April 26, 2011

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.

</blockquote>

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.

</blockquote>

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:

<ol>

<li>Have you ever used a Mamiya 645 system?</li>

<li>If so, have you ever empirically tested whether or not a film flatness issue exists?</li>

<li>If not, why do you think you can speak with the authoritative tone you speak with in this thread? </li>

</ol>

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

q.g._de_bakker · April 26, 2011

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. 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? And regarding your (frankly, rather insulting) questions:

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.) 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? 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. 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? But no worries: just get a Contax 645, the Contax Vacuum Back, and 220 film. 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... ;-) 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...? ;-)

rishij · April 26, 2011

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.)

</blockquote>

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?

</blockquote>

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?

q.g._de_bakker · April 26, 2011

Rishi, You keep asking for the sake of asking. You do know what the results are. The results are such that they kept those many hundreds of thousands [etcetera, etcetera, etcetera]. 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. ;-) 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. 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). The result of your 'scientific test' should make you scratch your head. "Nothing in focus". Really? How could that be? And finally: again, resorting to insults does not help to swing your case in your favour.

rishij · April 26, 2011

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.

</blockquote>

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?

</blockquote>

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.

</blockquote>

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

q.g._de_bakker · April 27, 2011

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? ;-)

rishij · April 27, 2011

"Many hundreds of thousands have tested their backs, day in day out, for many, many decades, and never seen any evidence."

</blockquote>

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."

</blockquote>

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?

rishij · April 27, 2011

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.

</blockquote>

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.

q.g._de_bakker · April 27, 2011

Rishi, 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. 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. 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. 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'. ;-)

rishij · April 27, 2011

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

</blockquote>

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?

rishij · April 27, 2011

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

rishij · April 27, 2011

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

q.g._de_bakker · April 28, 2011

Rishi, I do see your point, and it is flawed. 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. ;-)

rishij · April 28, 2011

I do see your point, and it is flawed

</blockquote>

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

</blockquote>

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

</blockquote>

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.

</blockquote>

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: <a href="http://www.thinkgeek.com/images/products/zoom/despair-poster-idiocy.jpg">http://www.thinkgeek.com/images/products/zoom/despair-poster-idiocy.jpg</a>

-Rishi

q.g._de_bakker · April 28, 2011

Rishi, One assumption:<blockquote>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)</blockquote>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'. ;-)

rishij · April 28, 2011

You certainly have concluded it does, based on no less than "with a little common sense & creative thinking". :D

</blockquote>

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.

</blockquote>

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

</blockquote>

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 ;-)

</blockquote>

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,

</blockquote>

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:

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.

</blockquote>

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

rishij · April 28, 2011

Here's the design of the film insert in the re-designed HM-401:

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

rishij · April 28, 2011

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.

david_dorcich1 · April 28, 2011

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.

q.g._de_bakker · April 28, 2011

Rishi, 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. Do you get the point? And how this is indeed very relevant to this thread? Perhaps not. 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? ;-)

rishij · April 28, 2011

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):

Top Center:

Bottom Left:

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):

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:

<ol>

<li>Unbent frame: 7 x 100 / 11.34mm = 62 lines/mm</li>

<li>Bent frame: 2.75 x 100 / 11.34mm = 24 lines/mm</li>

</ol>

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.

</blockquote>

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

richardsperry · April 30, 2011

Can I suggest the obvious?

Shoot the whole roll at one time.

rishij · April 30, 2011

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

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