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15 Exposure 120 Film Back for Mamiya 645 AFD


rishij

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<p>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.</p>

<p>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?</p>

<p>Just trying to step up from 35mm so any help would be greatly appreciated :)</p>

<p>Thanks,<br>

Rishi</p>

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<p>If you look at the this <a href="00NgFR">thread</a>, 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:</p>

 

<blockquote>

<p>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.</p>

</blockquote>

<p>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).</p>

<p>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.</p>

<p>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.</p>

<p>Hence my original question :)</p>

<p>Thanks,<br>

Rishi</p>

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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. ;-)
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<blockquote>

<p>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</p>

</blockquote>

<p>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?</p>

<p>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.</p>

<p>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.</p>

<p>Also, if a Pentax manual literally states it... that gives the issue much more gravity.</p>

<p>Cheers,<br>

Rishi</p>

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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! ;-)
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<p>Q.G.,<br>

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.</p>

<blockquote>

<p>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?</p>

</blockquote>

<p>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.</p>

<p>Check out page 76 of this: http://www.mamiya.nl/client/mamiya/uploads/downloads/645afdiii_manual.pdf<br>

Quote: "Under certain shooting conditions, the failure of the film to straighten out may cause<br />defocusing on part of the screen. When the camera has been left standing for a prolonged<br />period (30 minutes or longer) after the film is wound up, the frame following the<br />frame up to which the film was wound and at which the camera was left standing may be<br />adversely affected by the failure of the film to straighten out. In cases like this, the effect<br />can be prevented by setting the number of shooting frames to 15 frames for a 120 film or<br />30 frames for a 220 film. This failure of the film to straighten out differs significantly<br />depending on factors such as the type of film used and the temperature or humidity<br />during shooting."</p>

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Ray,<br><br>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.<br><br>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.<br>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 <i>that</i> bulge disappear to, do you suppose?)<br><br>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.
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<p>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?).</p>

<p>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.</p>

<p>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 <em>both</em> Mamiya <strong>and</strong> Pentax manuals.</p>

<p>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. <em>35mm film goes through no such rollers</em>. Which'd explain why I've never seen film flatness problems with 35mm.</p>

<p>Rishi</p>

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<p>LOL Q.G. Well played... well played.</p>

<p>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.</p>

<p>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.</p>

<p>Those tightly spaced rollers just make me worry!</p>

<p>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...</p>

<p>Interesting find with the Contax vacuum back. Did anyone ever definitively conclude whether or not it helped with 35mm?</p>

<p>Rishi</p>

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Rishi,<br><br>You're almost there. But not quite. ;-)<br><br>Seeing that you have <i>"never seen film flatness problems with 35mm"</i>, why even/still ask if a proposed solution to that problem (now, what problem would that be again?) helps?<br>You know the answer. You gave it yourself.<br><br>See now how it works?<br>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.<br>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 <i>"never seen [etc.]"</i>).<br>Strategic Marketing. The Dark Side of the Moon.<br> ;-)
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<p>Even these guys complain about film flatness especially with 6x9:<br>

<a href="http://www.hevanet.com/cperez/MF_testing.html">http://www.hevanet.com/cperez/MF_testing.html</a></p>

<p>I think you're following <a href="00YURs">this</a> forum, Q.G.... are all these people just crazy? </p>

<p>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.</p>

<p>Which makes me wonder: how does the pressure plate exert enough force without scratching the film back?</p>

<p>-Rishi</p>

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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. ;-)
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<blockquote>

<p>Which makes me wonder: how does the pressure plate exert enough force without scratching the film back?</p>

</blockquote>

<p>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.<br>

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.<br>

I think this is a case of trying to find a solution to a problem which doesn't really exist.</p>

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  • 2 weeks later...

<p>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. </p>

<p>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).</p>

<p>I'll do my own field test after getting the Phase One 645AF this weekend.</p>

<p>Cheers,<br>

Rishi</p>

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<p>Q.G. & Steve,</p>

<p>I find it hard to believe that all <a href="003kkW">these</a> people & <a href="001GYA">these</a> people are lying or deluded... it seems to be a real problem.</p>

<p>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.</p>

<p>I'll perform some tests over the next few days.</p>

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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.
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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

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"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.
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<p>As any scanning operator will attest to, bigger pieces of film are harder to hold flat... hence my lowered concerns for 35mm.</p>

<p>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!</p>

<p>I'm just trying to find a good test chart to shoot now to verify/debunk this problem :)</p>

<p>Thanks,<br>

Rishi</p>

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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...
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<p>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.</p>

<p>For the life of me I can't understand why there isn't more <strong>empirical</strong> evidence (read: <em>pictures</em>) showing that this is a <strong>real problem</strong> for 645 backs. Perhaps people don't like to waste film with such empirical tests.</p>

<p>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 <strong>millimeters</strong> 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 <strong>millimeters</strong> is?My jaw literally hit the floor when I saw this. In fact, the only film frames that are completely flat are the <em>1st</em> frame & any other portion of film that hasn't sat bent around the rollers for longer than what I would guess to be <strong>1-10 seconds</strong>. Taking a long exposure? Better throw away your next frame.</p>

<p>I'm utterly speechless.</p>

<p>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:</p>

<p>If you <strong>just</strong> loaded your film:</p>

<ul>

<li>1st shot: fine</li>

<li>2nd shot: crap (unless you loaded ur film & began shooting in under 30 seconds, which is impossible), so fire off 2 shots.</li>

<li>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...</li>

</ul>

<p><br />Not only is that a waste of film, but it's <strong>complicated </strong>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.<br /><br />Let me recap. If you follow the protocol I outlined above for your 16 exposure 120 roll, here's what you'll get:<br /><br />#1: good<br />#2: crap<br />#3: what #2 shoulda been<br />#4: good<br />#5: crap<br />#6: what #5 shoulda been<br />#7: good<br />#8: crap<br />#9: what #8 shoulda been<br />#10: good<br />#11: crap<br />#12: what #11 shoulda been<br />#13: good<br />#14: crap<br />#15: what #14 shoulda been<br />#16: good<br /><br />And all that will only be the case if you fire the following shots in rapid succession:<br /><br /></p>

<ul>

<li>2+3</li>

<li>5+6</li>

<li>8+9</li>

<li>11+12</li>

<li>14+15</li>

</ul>

<p><br />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 <em>does actually exist</em>.</p>

<p>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 <strong>literally</strong> 90º bends under tension, on the film roll. So the film roll doesn't introduce flatness issues; the rollers in 645 backs do.</p>

<p>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:</p>

<p>Total length of usable 120 film: 16 exposures x ~42mm = 672mm</p>

<p>Now if the film should be advanced an extra 21mm for each frame, that means that each frame now takes up 42mm+21mm = 63mm</p>

<p>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.</p>

<p>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...</p>

<p>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. </p>

<p>Here is the 1st frame of film after loading... notice it's <em>relatively</em> flat (not entirely so; look at the curvature on the left side):<br>

<img src="http://rishisanyalphotography.com/ForumPostFiles/photo.net/Mamiya645FilmBack_Frame1.jpg" alt="" width="800" /><br>

Here's the 2nd frame, after sitting overnight. Notice it looks like someone literally picked up the Velvia film & <strong>bent it in half</strong>:<br>

<img src="http://rishisanyalphotography.com/ForumPostFiles/photo.net/Mamiya645FilmBack_Frame2.jpg" alt="" width="800" /><br>

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.</p>

<p>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.</p>

<p>-Rishi</p>

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<p>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.</p>

<p>Does anyone know off-hand the distance between frames for 120 rolls shot with 16 exposures (in mm)? I can update my calculation then.</p>

<p>Thanks,<br>

Rishi</p>

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