FotoDave@aol.com
Thu, 18 Feb 1999 15:28:07 -0500 (EST)
> How can I determine the speed of an emulsion?
> I am preparing some silver gelatin emulsion and I'd like to know its
> speed.
I believe there is ANSI standard for the strict definition of film speed, but
I am not sure if that is what you are asking. I think you want to do something
similar to what we discussed about a week ago, that is, using a photometer or
an exposure meter to determine the exposure your the liquid emulsion? If that
is the case ....
> I guess that I can read the lux amount in my enlarger with my photometer
> and them find out by testing strips the minimum time to get the darkest
> black but how do I calculate the emulsion speed?
then you can find the time that gives you a density above base + fog (formal
speed tests use 0.10 I believe, but you don't *have to* use that figure; for
example, since lith film has a relatively long toe and I want nice separation,
I use about 0.20 + base+ fog.) If you don't have a densitometer, you can find
the time that gives you first visible fog (above base density) or slightly
above that.
I also found that in your email, your address appears in the "reply-to" line,
which is nice. :)
Dave S
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:06:51