making enlarged negatives (not just for PT/PD)

[Judy Seigel <jseigel@panix.com>]

Whether you call it "enlarging" or "copying", when you make a new negative
from an existing one, you can adjust it quite dramatically -- depending on
the film used & the processing (exposure & development). Which is to say,
"sensitometry."

All film work involves sensitometric concepts: that's how we control tone.
(And I daresay Photoshop does too, tho it's called something else.) It's
also easier & more satisfying to match the new negative to the process you
plan to use. (There are other processes besides pt/pd and not all want the
same negative, although some will oblige.)

If you print the intended emulsion a time or two with a Stouffer 21-step,
you see how many steps it prints, hence how many steps the large negative
needs.  The white cards on the light table method is best way to match new
neg to the printed 21-step. When you make enlarged negatives in future,
it's convenient to read the film test strips on the densitometer, if you
have one, but not essential.

I'll add that Post-Factory #1 had a 3-part article titled "Sense and
Sensitometry" which explained all with diagrams, illustrations, &
21-steps. And nobody that I know of swooned from the "S" word.

Judy