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  1. #1
    BetterSense's Avatar
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    contrasty/noncontrasty lenses?

    I never really noticed a difference in the contrastiness of camera lenses before, but I bought an Olympus XA and despite that I'm shooting at a lower EI (800) than I usually do when using Diafine, my negatives are needing 1-1.5 grades less contrast than they do on my SLR cameras. Could it be that the strange f/3.5 lens on the XA is a 'more contrastier' lens?
    f/22 and be there.

  2. #2

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    I am not familiar with that particular lens, but it could be you're slightly over or underexposing your negatives on your SLRs, that could cause a loss in contrast. Lens flare causes loss of contrast. And yes, lens coatings/designs/accuracy causes losses (or gains) in contrast. A Holga lens is less contrasty than a Nikkor 50mm 1.8 for example, ceteris paribus.

    The most probable answer (outside of lens flare) is over or underexposing your negatives. Incorrect exposure either way will yield a less contrasty print.

  3. #3
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    Yes, why not bracket a roll and see if the exposure is the reason. Anyway, you're not using an XA, right? It's an XA2 or similar? If so then you are probably (auto)metering quite differently than you might on an SLR or the original XA.

    I don't recall seeing especially high contrast from the XA or XA2 cameras that I've used. Could be that the XA2 lens is a bit contrastier but even so I doubt it'd have that much effect on contrast grade. Probably an exposure issue.
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  4. #4
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    Contrast in lenses might make huge differences, depending on the subject you shot (ex: landscape or portraits). It is accurately measured by the MTF graphs. Unlikely to film, the MTF curves are measured differently (at 3-4 resolution values across the lens radium, not on a continuous resolution scale). You also have multiple grafs for multiple aperture values.

    To learn if a lens is more contrasty than another for a specific aperture, you should look at the distance between the 100% line and the first MTF curve, than at the distances between this first MTF curve an the rest of them. If all MTF curves are grouped close to the 100% line, than you have a high contrast lens. If only the first curve is close to the 100% line, than the distances between curves is gradually increasing, you are on the low contrast side. Finally, if even the first MTF curve is far from the 100% line, you either have a bad lens or the wrong aperture. Because looking at the graphs for different apertures, you’ll also learn at what values your lens works at its best.

    You should also look for the fall-of of each MTF curve (the center of the lens is at left, and the margin at the right of each curve). This fall-of might be undesirable for landscapes, while being suited for portraiture.

    Check this site for some examples and further explanations: http://www.photodo.com/
    Last edited by phenix; 07-22-2009 at 11:02 PM. Click to view previous post history.
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  5. #5
    BetterSense's Avatar
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    I have an XA2. I set the dial on 800. The thing that confuses me, is this is MORE exposure than I usually give on my SLR cameras when I shoot at 1250. It looks like the negatives are at least as dense, too. Giving more exposure is supposed to decrease the contrast of the negatives.

    So even though by the numbers I'm giving more exposure, the negatives are still coming out contrastier. I usually print my diafine-developed negatives at grade two or three, but tonight I had to print at grade 1, and then I started falling back to split-grade printing where I was giving rather short high-contrast exposures (14s at 00, 5s at 5). Typically I end up with comparable times for the 00 and 5 exposures.

    It could be the developer is migrating or something, too.
    f/22 and be there.

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    http://www.flickr.com/groups/olympusxa/pool/ - You tell me.

    I've found that XA images tend to look contrasty, and the images in this flickr pool tend to support that assumption in my opinion. People often talk about the XA/XA2 in the same sentence as the LOMO LC-A since they both have very contrasty lenses.

  7. #7

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    Quote Originally Posted by BetterSense View Post
    I have an XA2. I set the dial on 800. The thing that confuses me, is this is MORE exposure than I usually give on my SLR cameras when I shoot at 1250. It looks like the negatives are at least as dense, too. Giving more exposure is supposed to decrease the contrast of the negatives.
    But you'll need to decrease development time. It seems that you overdevelop your negatives, resulting in high contrast.

  8. #8
    BetterSense's Avatar
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    Diafine has a fixed development time. I can't adjust development; there is no overdeveloping.

    The only way to adjust contrast with Diafine is to change exposure, and less exposure results in more contrast, more exposure results in less contrast. I think I'm going to try pushing to 800 with conventional developers in this camera.
    f/22 and be there.

  9. #9
    c6h6o3's Avatar
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    Quote Originally Posted by phenix View Post
    To learn if a lens is more contrasty than another for a specific aperture, you should look at the distance between the 100% line and the first MTF curve, than at the distances between this first MTF curve an the rest of them. If all MTF curves are grouped close to the 100% line, than you have a high contrast lens. If only the first curve is close to the 100% line, than the distances between curves is gradually increasing, you are on the low contrast side. Finally, if even the first MTF curve is far from the 100% line, you either have a bad lens or the wrong aperture. Because looking at the graphs for different apertures, you’ll also learn at what values your lens works at its best.
    I simply loaded a roll of film into my Hasselblad, made six exposures with the 80mm Planar, then changed to the 150mm Sonnar lens and shot the rest of the roll at the same aperture.

    The Planar negatives are about 1 contrast grade more dense in the highlights than the Sonnar ones. I know that this is not overall density I'm seeing because the shadow density is the same for all the negatives.

    So, to answer the question: Yes, some glass is more contrasty than others, even from the same manufacturer-Zeiss in my case.

  10. #10

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    Quote Originally Posted by BetterSense View Post
    Diafine has a fixed development time. I can't adjust development; there is no overdeveloping.
    Diafine produces excessive contrast with many films, so you could consider it as overdeveloping compared to a conventional developer.

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