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Re: Exposure question

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Chris Wright
Re: Exposure question
on Aug 15, 2016 at 5:28:34 am

I agree 100% with Tero.

If you look at the rec. 709 curve, most of the bits are spread toward the middle luma, because shadows and highlights have less bits to work with in 8 bit.

human eyes need a delta of 1% to not see banding. so linear light needs to be at least 14bits.

Since most cameras are only 8 bit, in the rec.709 gamma curve, the contrast ratio cannot exceed 50:1 or just a few f-stops.

With lower end cameras, the latitude range is less than 14 so you're having to share only around 8 f-stops, leaving about 3 and half above and below the middle!!!

So, as a rule of thumb, what you actually want to focus on is the f-stop difference between the middle and shadows so you can decide how to compromise on highlights being blown out without getting muddy blacks. You'll need a light meter to gauge the 3.5 f-stops from fill light to shadow light.

Hope this clears it up a little.

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