shadow detail vs contrast

That's a good question - I've seen the two mentioned side by side and often wondered the same.

Theoretically, I think Shadow detail would be how the lens reacts to the darker spectrums of light that come through it, and contrast is how much the whole tonal properties compress together.
 
contrast is the difference between the darkest dark and lightest light. shadow detail is essentially the contrast of the shadows, aside from resolution. the former is a function of the lens and recording medium (bw, color neg, chrome, digital). the latter depends on exposure, the recording medium, and development, printing, and postprocessing.
 
I think it is actually very simple. An ideal lens, with 0% light loss due to surface refraction of its elements, will reproduce the scene with the real contrast, i.e. you will get the same number of f stop difference between the highlights and shadows "behind the lens" as in front of it. The bigger is the percentage of light loss due to internal surface refraction, the smaller will be the contrast range "behind the lens". Since the highlights are pretty dense (we are talking negative film here) already, the biggest visible difference will be in the shadows, which will gain density, creating an illusion of the shadow detail. Translated into real life, lenses with no coatings, or older coatings, and imperfect internal construction (where you can get internal reflections from the lens barrel too), will produce far less contrasty results than the modern lenses ( will "glow" and produce brighter shadows) , than for example the latest Zeiss lenses with the most advanced coatings.
 
Shadow detail: amount of detail in the darkest areas ('shadows'). Depends on exposure.

Contrast: A continuum from low (shades of cigarette ash) to high (soot and whitewash). Depends on development and on flare factor (see below).

Microcontrast: Ability to deliver very fine detail. Depends on lens resolution and flare factor.

Flare factor: As mfogiel says, a flare-free lens in a flare-free camera will project an image with the same brightness range as the subject, e.g. 200:1 on the subject will be projected as 200:1 on the ground glass/film/sensor. This would be a flare factor of 1 (obviously it can't be less than 1). A very good multicoated triplet or Tessar in a well-blacked view camera can come very close to this.

The more spare light bounces around inside the lens and the camera body, the more non-image-forming light (veiling flare) ends up on the ground glass/ film/ sensor. Its effect in the brightest parts of the image (the highlights) is negligible but it 'fills' the darkest parts (the shadows). If, for example, the 200:1 brightness range of the subject is reduced to 100:1 by this, then the flare factor is 2 -- which is by no means unusual. Flare factors of 4 and above are known in box cameras.

Hope this clarifies it. There's more on my site.

Cheers,

R.
 
Thanks guys, you would think after almost 40 years of fooling around with this stuff I would know this.
 
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