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  1. #1
    wiseowl's Avatar
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    F-stop test strips

    I want to start doing my test strips using the f-stop method. So far I'm able to work out 1/2 stop increments, not exactly difficult even for my poor maths ability. However this has been a little coarse and I think it would work even better if I used 1/4 or finer steps.

    Is there a formula, or rule of thumb for calculating these small increments, or some other resource, such as a chart or table available? I know there is a timer which supports this feature but that is outside of my budget constraints, at least at the moment.

    Cheers

    Martin

  2. #2

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    Here is a chart that may be helpful. It is in Adobe pdf format:

    http://www.ktphotonics.co.uk/pdf/FstopTiming.pdf

    Regards,
    John

  3. #3

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    I have a trick for 1/3 stops if you happen to forget your math and your charts. Look at the light meter ISO settings; ISO 100 for 1 second, ISO 125 for 1.25 seconds etc. It is not high math but it is close enough for me.

  4. #4
    naaldvoerder's Avatar
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    Hi,

    On this site there is a compuetr programme available (for free) that will do all the sums for you.

    http://www.bonavolta.ch/hobby/

  5. #5

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    The formula is very simple :

    n
    Tb*2
    with Tb : Base Time
    n : Stop fraction ( -1, -1/12, ...,0, 1/12, +1)

    Eric.

  6. #6

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    you must read "2 power n" in previous reply.

  7. #7
    Jorge Oliveira's Avatar
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    There's one guy in the NET that made a freeware program for a Palm that will do that.
    I've designed for him an interface so the Palm can control an enlarger.

    I do not know his site, but if someone is interested, pls PM me and I will send his email.

    Jorge O
    Curitiba - nice place to live, if you don't care about the weather...

  8. #8

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    Here is another pdf chart that prints on a single piece of paper.

    My f-stop chart

    Kind Regards,
    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

  9. #9

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    It can't get any simpler than just printing out the chart. I used this until I bought a F-stop timer. Nice job on your chart GreyWolf..

    John



 

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