Re: colorsync-users digest, Vol 2 #596 - 1 msg
Re: colorsync-users digest, Vol 2 #596 - 1 msg
- Subject: Re: colorsync-users digest, Vol 2 #596 - 1 msg
- From: jeffstev <email@hidden>
- Date: Fri, 26 Oct 2001 15:57:15 -0400
Re: Ansel Adams
email@hidden writes:
>
Silver absorbes all colors, including infrared, almost
>
equally, so Ansel Adams never had this problem.
Robin Myers wrote:
Black and white silver halide
film
emulsions (the commonly used ones) are actually more sensitive to blue
and
ultra-violet than the infrared. To make a good panchromatic film (good
response
to all visible light wavelengths), special techniques were developed
(look in
Hunt's book "The Reproduction of Colour" for the details). Due to the
lower
infrared response of silver halide, to make an infrared film was a
rather hard
task.
I think Neil Barstow was referring to developed-out silver in prints and
negatives, not silver halide. Robin is quite right in quote above for
silver halide emulsions, which often incorporate sensitizing dyes (yes,
with black and white film) with the sliver halides in very compex
chemistry. The dyes are removed in processing.
Developed out metallic silver in emulsion can very in color from green
to brown to neutral to blue, depending on the size of the precipitated
silver grains. Toning can carry it to red, golden and many other
shades. Different photo emulsions, and developing and toning for warm or
cool color qualities utilizes this principle. Different silver halides,
as well as different manufacturing techniques and processing, will make
emulsions precipitate metallic silver grains in different sizes. Check
Wall and Jordan, Photographic Facts and Formulas, 1940.
Bill Burk wrote:
p.s. Checked Ansel Adams' *The Print.* He toned prints with selenium
toner,
and was concerned about subtle color changes observed when viewing print
under tungsten and daylight.
Quite true.
-Jeffrey Stevensen