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  1. #1

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    Neutral density filter question.

    I have an odd-ball neutral density filter. It's a Kodak Series VI and it says it is a 2.5. Looking around I see info on 2.4 and 2.6, but no 2.5.

    Does that number mean it is a number 2.5 and so about 8 stop, or is it a factor of 2.5 and so a little more than 1 stop?
    “You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  2. #2

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    Quote Originally Posted by pbromaghin View Post
    I have an odd-ball neutral density filter. It's a Kodak Series VI and it says it is a 2.5. Looking around I see info on 2.4 and 2.6, but no 2.5.

    Does that number mean it is a number 2.5 and so about 8 stop, or is it a factor of 2.5 and so a little more than 1 stop?
    You have it. Why don't you look through it? -1 stop doesn't look at all like -8 stops.

  3. #3
    LJH
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    Quote Originally Posted by Dan Fromm View Post
    You have it. Why don't you look through it? -1 stop doesn't look at all like -8 stops.
    Or just meter through it.

  4. #4

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    You have it. Why don't you look through it? -1 stop doesn't look at all like -8 stops.

    Hmm. Good question. It's the only neutral density filter I have. I've never dealt with them before and so have no basis from which to judge.

    I plan to be using iso 400 film in an old folder with a fastest shutter of 1/250. In the past a red filter has worked with B&W to get the exposure down to what the shutter can handle. I found this in the drawer and thought it would work for color film.
    “You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  5. #5

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    Quote Originally Posted by LJH View Post
    Or just meter through it.
    Another good suggestion. It's a Series VI which is quite a bit smaller diameter than any lens I have for a metered camera.
    “You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  6. #6
    RalphLambrecht's Avatar
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    Yes,81/3 stopsstops go in o.3 density steps0.1 density is a 1/3 stop.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  7. #7
    Bill Burk's Avatar
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    Hmm won't fit a camera with a meter...

    How about shining a light on a table with a beam that you can cover with the filter... Meter the light before and after.

  8. #8

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    Depending on the filter maker’s policy, ND filters can be marked in:

    1. Density units

    2. Stops of light absorbed

    3. Time multiplication factor

    I have examples of each type in my possession.

    For example, 0.40 ND = 1.5 stop = 2.5X time factor. Each value describes the same filter expressed in different units.

    I suspect that your “2.5” filter is time factor 2.5X.

  9. #9

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    From looking at this link, posted by Shootar401, I suspect Ian is right. On page 17 there is a chart with densities, transmission percent and fraction, as well as multiplying factor. Factor 2.5 is listed but the densities go only to 2.0, which is 1% transmission. Factor 2.5 would make this one a ND 0.4.

    https://archive.org/stream/WrattenLi...search/neutral

    Thank you all for helping
    “You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt

  10. #10

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    Now that I have seen the filter in good light, I feel really stupid for even starting this thread. It says very clearly on the edge of the filter - 2.5x multiplication factor - meaning a little over 1 stop. Thanks to all of you for your help.
    “You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live.” - John Galt



 

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