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Subject: Re: Exposure to the right and tone placement

Jeff Schewe wrote:

"Well, if you want a black cat to look black on a dark background and see any fur on the cat, you would indeed need to "over expose" to get any detail in the fur. Just because the cat is "black" doesn't mean that's what you want it to look like. Ever shot fur? I have. You have to pump a lot of light into fur in order to get detail whether you are shooting film or digital."

That's not answering the question, Jeff. Are exposing the cat at Zone IX to get the maximum number of tones? I hope not. You totally ignored my comments on how tone values can be distorted by improper placement prior to rendering. Do you dispute that this can occur?

"Look, you can TRY to dispute linear capture all you want and pretend it's just like film-but all that's gonna do is lead you down the path of always fighting the reality of the technology. Rag's lengthy theory not withstanding, digital sensors are photon counters. . .but unlike film, they respond in a linear nature."

No one is disputing the linear nature of linear capture. Heck, if you had read my post you would have seen I went to the trouble of getting a 16 bit linear capture for analysis. Film is also a photon counter, but analog with a log response, giving more values in the lower tones where they are lacking with digital. Fortunately, with modern sensors and techniques, this limitation can be overcome and I fully embrace the new medium and am not fighting it. The eye exhibits a log response and that is the end product of photography with either digital or film.

"As for the histogram, if you are talking about the camera histogram, forget it. At least on Canons, they are based upon the luminosity of the sRGB camera conversion. The highlight warnings are a full stop too conservitive and if you only use that histogram, you almost always lean toward under exposure. Far more useful and accurate is Camera Raw's histogram that is based upon the color space you are converting to and can shot you clipping either in the histogram or using the video lut animation of clip points."

With regard to video LUT animation, that was removed from Photoshop in Ver 6 and even before that was available only on the Mac. What version of PS are you using?

The luminosity histograms on cameras have been discussed previously. As I understand it, the newer professional Canons and Nikons show individual histograms of each channel and might be more useful. Perhaps someone can comment. The pertinent histogram under discussion here is the composite RGB histogram of the dark skinned person in Rags' treatise. If you want to contribute to the discussion in a useful way, you could comment on the standard deviation of the tones with underexposure, normal exposure, and over exposure and how this affects tone rendering.


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