No! Photography Nonsense-Unicorns: More wrong claims about FX lenses on DX cameras

by Staff September 17, 2016 at 9:48 am

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15 Comments

  1. Jeez Ken. Mount a lens with a collar on a tripod and show people the difference between dx and fx. same subject, same focal length , same distance, same aperture. Some people just don't get what a crop is. And here's what you don't get: One way to compare 2 different cameras is to take 2 pictures with an identical field of view, which isn't really possible when comparing dx to fx. But you can: A: crop the fx image in post (gonna cost a lot of resolution) B: put a wider lens on the dx (does increase the DOF) C: move the dx camera back (does also increase the DOF). Reality just isn't as simple as your correct theory.

  2. I've always wondered about this but I think there is a reason he claims so.
    If you look at DXO mark results, all FX lenses score less in sharpness when used on
    DX bodies with the same MP counts.

    For example,
    35mm 1.8
    16~17 on d7100, d5300
    19~ 21 on d610, d750

    60mm 2.8G
    11 on d7100, d5300
    15~17 on d6100, d750

    Of course this could just mean larger sensors yield better sharpness so I looked for
    DX and FX lenses of similar age and focal length,

    Sigma 30mm 1.4 DC
    15 on d7100

    Sigma 35mm 1.4 DG
    16 on d7100
    22 on d750

    (I also looked at nikon 35mm 1.8's, the only pair of nikon DX and FX lens with same focal length and F number. FX one scored better on this comparison but I suspect the two
    weren't made with the same quality standards.)

    So, maybe there really isn't disadvantages to using FX lens on DX cameras.
    But at the same, perhaps there isn't advantages to it either(as some people like
    to claim it would utilize only the sweet spot of the lens therefore better sharpness).
    What's interesting is how larger sensors usually give sharper photos.
    The bottom line, as I understand is – buy dx lens for dx cameras. Its smaller and cheaper.
    Yeah.. DXO mark maybe bullshit but there is little reason to be suspicious of comparative sharpness scores.

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