Re: Grayscale perception
Re: Grayscale perception
- Subject: Re: Grayscale perception
- From: David Scharf <email@hidden>
- Date: Tue, 06 Dec 2005 05:47:45 -0800
Yes I can see that for 8"x10" output it is more difficult to attain the
desired light intensity onto the film. I have use my Celco Extreme fx16
for 4"x5" and 35mm and have had no problem achieving the full dynamic
range on such films as Kodachrome 25 (35mm), and for 4"x5", Ektachrome
100 and Fujichrome Provia 100 at 4k resolution. On the Celco, I have
control over the pixel dwell time, and thus the overall exposure. They
have also effectively solved the halation problem at high brightness
levels. (It also has a very nice Schneider APO lens). I calibrate a LUT
for each film type by generating known value step wedges for red green
and blue filters; reading the values with a densitometer and
programming in a correction value (using Celco software). Its been very
effective. I have no banding issues unless they are introduced with the
image file.
Best Regards,
David
jc castronovo wrote:
Mark is correct here. I'm quite
familiar with both LVT and CRT film recorders, the inner workings and
calibration of each. The Celco is very good, but no contender in
comparison to good LVT output. CRT output is even more non-linear in
the highlights than film and cannot reliably achieve a D-min of .08
either. Properly processed E6 film pretty much tops out at this
brightness level which makes this a difficult thing to maintain. A more
realistic aim is .10 which is still brighter than Kodak's aims for the
LVT, but CRT recorders typically shoot for .20 or darker for a
highlight to avoid the inherent flare of the tube and the more complex
optical system. The darker aim and the flare of the CRT recorder helps
to mask highlight banding. I have very few issues with banding in
either my LVT or CRT film output unless it's in the file to begin with
(generated blends are clear offenders) in which case we have to add a
little noise, but I've learned not to push the envelope beyond it's
limits. We also process our own film and make custom profiles for our
output which helps tremendously.
---- Original Message -----
Sent:
Tuesday, December 06, 2005 2:57 AM
Subject:
RE: Grayscale perception
I was referring to large
format film recorders. For retouching purposes, we had to achieve a
D-Min of about .08, which required very high light output, as the film
is extremely non-linear in this region. It's also the region where is
is extremely difficult to achieve smooth gradation.
Mark
Mark,
I have to disagree. I have been using a Celco film recorder for 10
years. It has 16 bit LUTS and 16 output to the CRT. Extremely
repeatable and stable in color and geometry (it has to be for motion
picture film use). Today its still one of best film recorders you can
get. I stopped using it a couple of years ago because my clients no
longer want transparencies, just digital files. It's for sale now if
you want the best....
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