Reciprocity failure and Fuji 100C?

winger

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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.
 

Lee L

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The attached should help.

Lee
 

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  • fp_100c_datasheet.pdf
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Lee L

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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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  • FujiFP100CReciprocity.pdf
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Last edited by a moderator:

Lee L

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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
 
OP
OP

winger

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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.
 

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  • imgd385-sm.jpg
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