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Translating F-Stops and the Zone System to Digital

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Max JacksonTranslating F-Stops and the Zone System to Digital
by on Jul 28, 2010 at 3:39:26 am

If somebody were to ask me to drop a certain shot by a full stop say below Zone V how would that translate into Brightness/Contrast the hexadecimal system, or even more so levels and curves?

Is there a system to translate the analog process of aperture to digital?


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Steve RobertsRe: Translating F-Stops and the Zone System to Digital
by on Jul 29, 2010 at 11:58:17 am

An f-stop is double or half the amount of light. An f-stop over is twice as bright, and f-stop under is half as bright. The Zone system is based on f-stops, so Zone IV is half as bright as Zone V, which is half as bright as Zone VI. Zone V is middle gray, the same as an 18% reflectance gray card, which some quote at R=G=B 117 for gamma 2.2.

However ... regarding RGB, apparently Lee Varis sets the R=G=B values at this, for zones 0 to 100:
0-33-51-72-94-118-143-169-197-225-255.

Now if you're a really anal Zone guy, you might want to do your own densitometer/paper testing as gamma (among other things) are an issue. Your mileage may vary.



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