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  1. #11
    DanielStone's Avatar
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    I use Nikon F4's

    Considering the 'hassle' involved with the de-clicking of the AI/AI-S lenses(5 of them total), THEN paying to get them each individually t-stopped, I'm guessing that it'll probably be upwards of ~$1k or so, thats a LOT of film for the freezer !

    So, seeing that I'm NOT doing any video work, just stills, I've realized that it's not going to be worth it.

    thx,
    -Dan

  2. #12

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    Your original findings are interesting though; it makes me want to do DOF tests also. I wonder if making multiple shots with the same exposure would still show discrepancies.

  3. #13
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    Quote Originally Posted by benveniste View Post
    I'm not going to comment on Mr. Rockwell as a source in general, but as a long time FA owner, I can tell you that the FA only applies "last look" corrections in S and P modes and not A nor M modes. So for DOF purposes, Mr. Rockwell's claim is a red herring. If you think about how Nikon's aperture lever works, you'll see this has to be the case. (From language in the manual, I think it only applies such corrections when it can't detect an AI-S or Series E lens, but I'm less sure of that.)

    You might be able to get a lens re-engraved with T-stops, but unless you also recalibrated the detents you'd still be shooting in f/stops. Since DOF is a subjective "acceptably sharp" criteria to begin with, I suggest you relax, don't worry, and save your money for outings, film, prints, etc.
    Thanks for the clarification and the nice writing!
    Fed 2, 4, 5
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  4. #14
    Jim Jones's Avatar
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    It's easier to calibrate people than to recalibrate lenses to T-stops. Once you've determined the required offset to correct to T-stops, apply it when calculating the desired exposure.

  5. #15

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    Quote Originally Posted by LJSLATER View Post
    I've tried de-clicking an AIS Nikkor. Removing the click-tab also removes any and all resistance on the aperture ring, so it's free to just turn on its own. In addition to feeling like garbage and occasionally making a fingernails-on-chalkboard noise, the aperture ring moves on its own when attached to the camera since the metering coupler on the camera is spring-loaded. I took some pictures of the lens parts below so you can see how de-clicking/re-clicking the aperture ring would work in theory. I don't know if all Nikkors are built like this, however.


    Nikon 50mm f/1.2 AIS by LJ Slater, on Flickr

    Nikon 50mm f/1.2 AIS by LJ Slater, on Flickr

    Regarding the exposure discrepancies, I too would be interested to know which camera was used? The F5/F6 are supposed to have shutter monitoring systems that makes corrections as needed. My guess would be that the manufacturing tolerances in Nikkors are not up to your standards, Mr. Stone :P

    There are lots of "T-stopped" cinema lenses for F-mount bodies, but they appear to be upwards of $3K each.
    I found the apertures on Nikkor lenses are very accurate. I have no complain. I found even with the F5 the shutter speed accuracy still not very good.

  6. #16

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    Are you also going to get the shutter speeds checked for accuracy and, more importantly, repeatability?

  7. #17
    PhotoJim's Avatar
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    I assume you're not using TTL metering? If you are, T-stops won't help you because the camera is not measuring what the aperture says it is - it's measuring the light that's being transmitted when stopped down to that aperture. An inaccurate shutter or sticky diaphragm can contribute to exposure errors of course (as can a miscalibrated mirror) but getting the camera and lens properly adjusted should eliminate the problem completely.

    If you're using a handheld meter, I can see the benefit in T-stops but the light transmission of most lenses for 35mm photography is so good, it isn't likely to make a significant enough difference, even with chrome film. You'd need 15 or 18 elements, I'd think, before it started to make enough of a difference compared to using f/stops.
    Jim MacKenzie - Regina, Saskatchewan, Canada

    A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.

    Favourite film: do I need to pick only one?

  8. #18
    DanielStone's Avatar
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    Hey Jim,

    Not sure if you're talking to the other(F5) guy or me;

    If me, I DO use a handheld meter. Hardly ever use the in-camera meter unless I seemingly forgot to put the meter in the bag prior to departure .
    A cinema-meter in fact, a Spectra IV digital. Wonderful meter, super accurate, and great for VERY low-light exposures as well(which I'm starting to do more of, @ dusk, etc...)

    -Dan

  9. #19

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    I was under the impression that T-Stops hade to be recalibrated every so often... I imagine that'd be fairly pricey in the long run.
    "Art is is a picture of some dude I never met smoking under a lamppost at 6400 ISO and in BW."

  10. #20
    skahde's Avatar
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    Hi Dan,

    if you really need to be sure, you can always use stop-down metering if your camera provides it. The difference between your measurement off-camera and the value measured via TTL should remain constant with changing f-stops. You will probably never catch the source for the minor variations you describe, though. I'd start with having the shutter checked and - if neccessary - calibrated.

    best

    Stefan

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