[pure-silver] Re: Blue Water
- From: Luis Miguel Castañeda <lmc@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Wed, 20 Sep 2006 08:23:39 +0200
On 19/09/2006, at 23:24, Georges Giralt wrote:
I do not know exactly why this does not happen so heavilly in
135 film, but sometimes there is a faint color for 135 film.
because most 135 films have a coloured base.
Yes and no.
Tmax film have a distinctive purple cast as anti halation layer but
this one goes with chemical reaction in the dev and fixer and is
eliminated in the final wash.
What exactly make 120 film different is a mystery to me !
Most 120 films like FP4 or HP5 used to have a clear base, as opossed
to 135 that used to have a gray base to prevent halation and light
scattering over the emulsion, but that's only a rule of thumb and a
quick and dirty explanation.
You can find films like foma that use a blue polyester base in 120
that have those layers, and other films in 135 that uses them, as
Richard Knoppow said, they could have a variety of functions (UV
filtering, sensitizing dyes, antihalation...). Anyway those are
concerns that the make already worried and noted in the tech sheet
for the most of us, so it's a technical curiosity more than anything
else for the practical photographer who already cared for their
materials.
Saludos
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