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  1. #1
    Modern Minoltian's Avatar
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    Is there any database online of legacy lens T-stop ratings?

    Or is there perhaps a way I can determine it on my own?
    I know it's not usually that different from an F-stop, from what I understand, I'm mostly just curious.

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    Is there any database online of legacy lens T-stop ratings?

    Quote Originally Posted by Modern Minoltian View Post
    Or is there perhaps a way I can determine it on my own?
    I know it's not usually that different from an F-stop, from what I understand, I'm mostly just curious.
    T stop? I've never seen that and I have some cameras from the 1910's how old is that "system"?


    ~Stone

    Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

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    Is there any database online of legacy lens T-stop ratings?

    Are you sure you don't mean like the B/T/I settings on an old lens? T means time, which is like Bulb except it will stay open after releases and only close after you click the trigger a second time, often used for very long exposures.


    ~Stone

    Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

  4. #4
    MattKing's Avatar
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    Quote Originally Posted by StoneNYC View Post
    T stop? I've never seen that and I have some cameras from the 1910's how old is that "system"?


    ~Stone

    Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk
    T-stops are used primarily for motion picture lenses - they provide a more exact measurement of the light transmission of a lens then the slightly more theoretical f-stops.

    The difference is usually small, and generally only relevant in the exacting circumstances of motion picture work.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  5. #5
    Modern Minoltian's Avatar
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    Quote Originally Posted by MattKing View Post
    T-stops are used primarily for motion picture lenses - they provide a more exact measurement of the light transmission of a lens then the slightly more theoretical f-stops.

    The difference is usually small, and generally only relevant in the exacting circumstances of motion picture work.
    Exactly. It's the standard measurement used for cinema lenses, it's the F-stop corrected for absorbance and reflectance. It is usually very close to the F-stop, I was just curious as to whether some manufacturers' lenses might be more affected by absorbance and reflectance than others. But I guess guess if the T-stop was never given by the manufacturer, it'd be pretty hard to figure out.

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    Is there any database online of legacy lens T-stop ratings?

    Quote Originally Posted by MattKing View Post
    T-stops are used primarily for motion picture lenses - they provide a more exact measurement of the light transmission of a lens then the slightly more theoretical f-stops.

    The difference is usually small, and generally only relevant in the exacting circumstances of motion picture work.
    Oh well don't I feel like a fool, especially because I work in the movie industry haha (but not on the camera crew side..yet).


    ~Stone

    Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk

  7. #7
    Ian Grant's Avatar
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    It's also worth bearing in mind that the transmission of lenses improved very significantly with the advent of coatings in 1938 although it was after WWII when coating s became universal on all quality lenses.

    The first coated lenses from Zeiss have a red "T" designation for Transparent, earliest I've seen was a 1938 CJZ 15cm f4.5 Tessar, I have an early 1950's version and the coatings are excellent althogh a touch blue for colour work.

    Before coating was commom many photographers processed to higher negative contrasts to help overcome slight lens flare, by the early 1960's this had changed and the ASA/BS testing of films was revised resulting in nominal film speeds being doubled (Tri-X went from 200 ASA to 400ASA).

    Ian

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    before WW II the old f-stop system was often used: 2.2 / 3.2 / 4.5 / 6.3 / 9 / 12.5 / 18

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    Quote Originally Posted by Modern Minoltian View Post
    Or is there perhaps a way I can determine it on my own?
    I know it's not usually that different from an F-stop, from what I understand, I'm mostly just curious.
    I don't have any lens-specific info for you, but do have an old standard, Method for Determining Aperture Calibration of Motion-Picture Lenses. It's USA Standard PH22.90-1964 (reaffirmed in 1969). This was the standard for determining both f-stops and t-stops back in the day.

    It's too tedious to describe, but if you look up Appendix II at the following link, it looks like the same basic info: http://www.archive.org/stream/journa...irich_djvu.txt

    Even if you can dredge through it, my guess is that you'll decide you can live without t-stops.

  10. #10
    Ian Grant's Avatar
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    Quote Originally Posted by jochen View Post
    before WW II the old f-stop system was often used: 2.2 / 3.2 / 4.5 / 6.3 / 9 / 12.5 / 18
    Not by many manufacturers, my 1913 CZJ 165mm f6.3 Tessar has the tradional 3, 5.6, 8, 11, 16, 22, 32, in fact of all my pre-WWII German lenses (over 16) only my Summar has the other syste.

    Ian

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