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Subject: Re: Exposure to the right and tone placement





Truths: 1) Light intensity varies by log base 2 as distance changes.




Uh uh. The intensity of a light source varies by the inverse square of the distance, not the log. By the same token the size of an object varies by the same amount, and therefore objects do not get dimmer as they get further away. This is gnoring atmospheric effects, which are generally proportional to the inverse of the distance.

2) Exposure values are scaled by light flux at log base 2.




Not quite. Flux is related to light intensity. E.V. includes both intensity and time.

3) Digit encoding is based on bits scaled at log base 2.




No. The log 2 is due to the binary numbering system. This has nothing to do with the encoding of the data, which is approximately linear.

Happy new year to all.

Mike Russell

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