01-10-2017, 12:17 PM
Quote:Most film has DR much lower than 10 stops.
Slide film, loved for its colours and punchy nature, has very unforgiving, low DR, 5 to 6 stops.
Colour negative film ranges from more punchy and contrasty types (the types most used) 7 stops to lower contrast maybe past 10 stops.
Black and white negative film ranges from high contrast to very low contrast, upto 12 stops. Most photographers never used the very low contrast types, they were for specialized jobs.
Some confuse the DR one can achieve with the forgiving nature of some film which allows one to under expose (by accident) and still develop the images and get the same 5-6 stops of DR.
High DR is either very low contrast, or not visible to us (our eyes at any one time see about 6.5 stops DR), or tone mapped to something unrealistic. One can print very low contrast, and one can print tone mapped unrealistic stuff.
A high DR of 12 stops means saying what we see as white is a grey and white is further up the range, and saying what we see as black is a grey and black is further down the range. That is why high DR is low contrast.
Screens have been getting more and more contrasty, not really getting a higher DR for our eyes.
Often teh upper and lower few stops were very limited with B&W film, because they resided on the curves of the gamma curve. Effectively you normally had a maximum of 10 stops, based on my own experience. Low contrast is relative; I used Kodak Panatomic-X most of the time, I think rated at 50 ASA, and exposed it dependign on what I wanted to achieve, between 20 and 125 ASA, and developed accordingly. This most people would see as a relatively high contrast film, but worked perfectly for me .
I assume that with the 6.5 stops the human eye can see, you mean what the human eye can see in a single instant. Because the human eye (and brain) can adopt very quickly, what we can perceive in a scene is about 17 stops, as far as I am aware based on teh literature I read over the years. This is because the eye and brain can adapt quickly enough that we don't notice the transitions.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....