From: Sandy King (sanking@clemson.edu)
Date: 04/08/03-05:42:29 PM Z
Greg Schmitz wrote:
>Scott:
>
>I don't want to rain on your parade, but it has been my experience
>that it is almost impossible to raise the true speed of any film - no
>matter what. I have exposed and developed hundreds, perhaps thousands
>of rolls of test film. In reality what is usually meant by an
>"increase in speed" is really an increase in contrast. The point at
>which the films curve begins to pivot upward does not change, it just
>gets steeper. I have seen minimal increases in true film speed with a
>few special additives, pre/post-exposure, and exposing film to certain
>gas fumes.
Yes to all of the above. About the most *real* increase in effective
film speed with any developer over the manufacturer's recommendation
is about 1/3 of a stop. Film speed does increase with CI, however, so
an effective film speed for a specific film/developer combination
for printing in silver where the CI needed is about .52 will be less
than what you will see with the same combination when developing for
an alternative process where the needed CI is over .70.
Sandy King
This archive was generated by hypermail 2.1.5 : 05/01/03-11:59:54 AM Z CST