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  1. #1
    winger's Avatar
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    Reciprocity failure and Fuji 100C?

    If I were doing an exposure using Fuji100C that metered as f16 for 15 seconds, how much should I adjust if any? I'm getting shots that still look dark compared to the scene, but I don't want to go just by guessing. I've used 20 seconds and 25 seconds. My favorite, best-ever app for this has every film I've ever used, but not instant film.

  2. #2
    Lee L's Avatar
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    The attached should help.

    Lee
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  3. #3
    Lee L's Avatar
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    Ran the numbers from the Fuji datasheet. Schwarzschild exponent calculates consistently to 0.5 at all the given data points.

    To calculate an adjusted exposure time (not aperture adjustment) it's:

    corrected exposure time in seconds = (t+1)^(1/p)-1

    where t is the metered exposure time in seconds and p is the Schwarzschild exponent

    Chart attached. Have fun.

    Lee
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    Last edited by Lee L; 01-04-2014 at 09:29 AM. Click to view previous post history. Reason: fixed ugly .pdf

  4. #4
    winger's Avatar
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    Thanks, Lee!

  5. #5
    Lee L's Avatar
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    You're welcome. I look forward to seeing the results.
    I revised the chart with a monotype font for a better reading table. Newly installed version of LibreOffice defaulted to Arial, horrible for this purpose, and looked worse in the .pdf. So you may want to download again.

    Lee

  6. #6

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    Yes, thanks for this very useful chart.

  7. #7
    winger's Avatar
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    I shot these before I had Lee's chart. The darker one (done first) was at f16 for 20 seconds. The lighter one was f8 for 20 seconds.
    Attached Thumbnails Attached Thumbnails imgd384-sm.jpg   imgd385-sm.jpg  



 

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