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.
As you can see the contrast range that slide can capture is around 7
stops. In general practice the normal black point is -2.5EV from grey
and white point is +2.5EV from grey. That means the white to black
different is 5EV that is most likely people using to test film (and
lens) resolution, as normally their target is black strip on white
paper.
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.
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).
C.H.Ling
"C.H.Ling" wrote:
>
> Yes, you are right! My math is really getting bad.
>
> C.H.Ling
>
> ----- Original Message -----
> From: "Thomas Bryhn" <thomas.bryhn@xxxxxxxxxx>
>
> >
> > 2^8 = 256, 2^10 = 1024
> >
> > Regards,
> > Thomas Bryhn
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|