At 03:15 28.09.01, you wrote:
After thinking again, I think both 8 stops and 10 stops are wrong.
1000:1 should be equal to around 5 stops only. Since contrast ratio is
linear ratio and EV or stop value is energy, which follows square law.
??? I'm not shure which square law you are talking about here. I assume
contrast is a ratio between two "amounts of light", photon counting if you
will. Energy is proportional to the number of photons if you don't change
their individual energies. To have the same ratio in stops you use the
base-2 logarithm.
If the ratio in contrast measurement is something completely different I
stand corrected.
Also, 1000:1 is equal to D-range 3.0. which is definitely not enough
for slides. If 1000:1 is equal to 10 stops, we will have no problem on
using such scanner for our critical works.
This is a major source of confusion: The density of a slide can vary from
0.2 to 4.0 in extreme cases. This is the density of the slide measured in
base 10, and has *nothing* to do with the 5-7 stops a slide film can hold
information about. For the sake of the argument we can say that a film pick
up details from exactly five stops, that is 5 stops from the real world.
After the film is developed you can measure the difference in density
between the darkest and lightest part of the slide. That difference can
easily be 3.0 or something. If you shine a light through the slide you will
then have a contrast range of (10^3.0):1 = 1000:1 = 10 stops. You can check
this by exposing one frame of slide film correctly, then another one under
or over exposed one stop, and then meter through the developed film later.
You'll find that the difference is now much more than one stop.
The film has increased the contrast, and this is the very reason that
special slide duplicating films has to be used to be maintain reasonable
contrast levels.
Again, LCD monitors has common contrast ratio of 1:350-500, which
still need improvement, obviously they think it is not enough to
compare with CRT. At the mean time you can see the Gas Plasma display
has 1:3000 contrast ratio which is using in Hi-end TV display. Do you
need a display to handle over 10 stops contrast different? No, I think
they are just close to the slide's quality and D-range of around 3.5
(between 5-6 stops).
3000:1 = 11.6 stops, or D = 3.47, that is indeed exactly like a slide!
(BTW, how much for a TV like that?)
A display is an active device, emitting light. 10-12 stops between two
pixels or lines shouldn't be impossible, it's still only a dynamic range of
60-72dB. If it where a reflective media I would agree that 10-12 is totally
unrealistic.
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