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Thread: Sharpness of Sheet Film vs Roll Film

  1. #1

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    Sharpness of Sheet Film vs Roll Film

    I have always maintained that b&w sheet film presents many operational drawbacks. No sound nor motion of video, no color, no fast and zoom lenses nor motor drives of 35mm, etc.

    The major, if not singular, quality which sheet film brings to the party is a remarkable ability to capture exquisitely fine detail. One often hears law enforcement people on the news lament the poor quality of digital surveillance pictures (which can’t be clearly enlarged) in bank robberies.

    In my technically sloppier moments I refer to this quality as sharpness. But, as a former college kid, I am aware that the proper terms are acutance and resolution.

    Twelve years ago, I worked for a friend who is even more technically anal than I am. His specialty was 8x10 Ektachrome, shot on a king’s ransom worth of Sinar and Broncolor equipment. Absolutely no expense spared. Everything absolutely perfect. Every time.

    One day, while doing a food assignment for a very young Boston art director, we caught her examining the 8x10 transparencies on the lightbox, using a loupe her boyfriend had given her to inspect 35mm slides.

    She declared that the chromes were “soft” and began to insist that the entire project be reshot.

    It took a great deal of fancy talking on the part of the studio owner to convince her that the 8x10 chromes were already the size they would be lithographically reproduced, and there was no point in looking at them through magnification. Finally, she backed off and the day was saved.

    I knew enough to make myself scarce during that discussion. But, you know, the girl had a point. Those sheets of color did not seem to my eye as “sharp” per square inch as 35mm and 120 roll film. Especially under a loupe.

    There is always the chance that the film could have bowed slightly from the center of the holder due to gravity. Anything was possible, except camera movement as we lit with the mighty Broncolors.

    But I sometimes wonder if thick emulsion (color especially) sheet film is somehow not quite so crisp as microscopically thin tabular grain 35mm and roll film.

    After years of doing b&w exclusively, color and chromogenic images always look slightly mushy to my eye. Perhaps that was it.

    What do you think?

  2. #2

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    Sharpness of Sheet Film vs Roll Film

    I'm a big fan of 4x5, 5x7 and 8x10 for black & white. But, but... I have this print hanging on my living room wall. It's my father, long since gone, fly fishing. I shot it with a Hasselblad w/150mm lens T-max 100 and on a tripod. He's standing on a dock and you see some dock and 8 feet of rod on a backcast. Take a magnifying glass and you can see I shot it at 1:20 according to his watch.

    I think it has a lot to do with film flatness and build quality of Hasselblad and Zeiss. The film plane and focus plane of high end M/F and 35mm equipment has to be way tighter than the best L/F.

  3. #3

    Sharpness of Sheet Film vs Roll Film

    I believe the emulsions are the same. Material used to adhere it to the base may be different amd the base is different.

    Looking thru the thicker base may make it appear softer.

    The lenses designed for larger formats have les resolution than those for 35mm. There is no reason for them to be as sharp as for 35mm. I must add I look at negs made from modern 4x5 lenses with a loupe for 35mm and they look sharp at 8x. I seldom enlarge them past 11x14 so they are fine.

  4. #4
    Whatever David A. Goldfarb's Avatar
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    Sharpness of Sheet Film vs Roll Film

    What was the shooting aperture, and was this tabletop work? She may have been seeing some diffraction if the lens was stopped way down and magnification was high--necessary to get the required DOF on 8x10", and the side effect of diffraction might show up with a loupe, but wouldn't really matter if the transparencies were not being enlarged significantly. A better comparison would be to look at two identical sized prints or dupes of the same setup from two different formats.

  5. #5

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    Sharpness of Sheet Film vs Roll Film

    "After years of doing b&w exclusively, color and chromogenic images always look slightly mushy to my eye. Perhaps that was it."

    I've noticed that too. I always thought it was because chromogenic print materials such as C prints had to have more color layers which physically affected the print acuity. When I started dabbling in color printing with an inkjet I noticed the prints looked sharper, and figured it was because a single layer of ink droplets could have more acuity. I never related this phenomenon to a difference between sheet film and roll film, however.

  6. #6

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    Sharpness of Sheet Film vs Roll Film

    If you want great sharpness in LF, then a vacuum or precision back is in order. Also, shooting at plane focus wider open would help. Restricting subjects to those that yield easily to sharpness helps as well. Kinda obviates many of the subjects we do, doesn't it? Unless you are into aerial photography, and then all that takes is a huge amount of money and an obsessive penchant for metric cameras.

    FWIW, the US Air Force and NASA has unclassified documents concerning their aerial recon efforts. Of course, a recon objective was to extract information which does not always mean 'sharp' images as we speak of sharpness, for example gleaning data using stereo images and expert brains, and then there's symthetic-aperture radar, and digital sensors. Yes, that's right, digital aerial imaging was being done in the sixties. The commitment was made quite early. By 1970, "pixels" was part of the ordinary language in certain efforts. I haven't tried to find info about those early NASA and military projects on the internet yet, but digital recon technology has been in printed literature since about 1970.

    Shaprness, per se, is not why I do LF, but the challenge to maintain adequate shaprness certainly keeps me on my toes.

  7. #7
    Resident Heretic
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    Sharpness of Sheet Film vs Roll Film

    From a mechanical standpoint, you loose some and you gain some. You loose when you decouple the lens from the camera body. You gain when you shoot from a tripod. You gain some more when your design doesn't have a swinging mirror or a focal plane shutter. You loose when you aren't using roll film that you can keep under tension. You loose a bit more as your film size goes up but your base thickness stays the same. You loose a little because your LF lenses aren't as sharp as the smaller format lenses. You loose a little because LF forces you to shot at smaller f/stops and corresponding slower shutter speeds.

    I think the "sweet spot" is 4x5. The film thickness is sufficient in relation to the film area that film sagging isn't much of a problem. The smaller cameras are more ridgid. The smaller cameras are also easier to work with - almost anyone can set all the movements from under the dark cloth while watching the ground glass. And film area is sufficient for huge prints from moderate enlargement factors, meaning that what sharpness you might loose, doesn't show in the prints.

    It is all a trade off, so of course YMMV.

    Bruce Watson

  8. #8

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    Sharpness of Sheet Film vs Roll Film

    No pressure plate holding the film absolutely flat. Possible film movement. Typically, somewhat better resolution numbers as you go down to smaller formats. Ability to shoot at larger f-stops with smaller formats, thus less diffraction losses and wind blur etc. Theoretically, all of this suggests that the position of the film should be more accurate in smaller formats and resolution should be better.

    And yet, LF seems to trump all these factors. First, smaller enlargement. Smaller format lenses may have better resolution at the negative but this increased resolution (typically along the order of about 50% for the best 35 mm lenses) does not seem sufficient to make up for the sometimes order of magnitude difference in enlargement. So, while the small format neg may be sharper, the print from it is not. Second, upto about 8x10, I have not found film movement to be a significant source of unsharpness (at least as compared to other sources of unsharpness), and as pointed out if funds permit, one could use vacuum backs etc. I suspect that while the theory may be sound, there is enough other noise in practise to swamp this small effect size. Third, keep in mind that a 1 mm error that can be quite significant in smaller formats may be much less consequential with larger formats. Finally, keep in mind that sharpness is a multi-headed hydra and all of this only addresses resolution. Other factors contribute as much to the subjective experience of sharpness and LF typically scores on these fronts. Take acutance. The lower enlargement typically translates into better acutance from an LF neg. LF also does better at holding micro-contrast (contrast in small areas). That is, little changes in tones are captured with more area in LF, whereas in smaller formats, they are sort of averaged or smeared onto the smaller area. Thus, the sensation of extremely fine detail in LF, even if that detail is less sharp theoretically.

    With regards to the B&W versus color/chromogenic, I have heard others comment on this and wondered whether it was the difference between silver grains and dye clouds but have also wondered if this was a systematically discernable difference.
    Cheers, DJ

  9. #9

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    Sharpness of Sheet Film vs Roll Film

    Lets us say that you are using 8X10 film and that camera is pointing down. Generally, can the most films support their own weight? That is, can the center of the film bow away from the holder? Also, are current films thicker than films from recent history or are they all pretty much the same?

  10. #10
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    Sharpness of Sheet Film vs Roll Film

    add to the list that you're using lenses that are designed for lots of coverage ... there are optical compromises involved in doing this. if you compare MTF curves of the best lenses in different formats, you'll see a general decline in performance, all else being equal, as coverage expands. however, you might be talking about a 20% drop in MTF, corresponding to a 100% increase in linear film size, so the compromis is more than worth it in the end.

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