The film data sheets should give corrections for long exposures. For
instance, for Tri-X,
the data sheet says:
Exposure time 1 sec; corrected exposure +1 stop OR adjusted exposure time
2 sec
Exposure time 10 sec; corrected exposure +2 stop OR adjusted exposure
time 50 sec
Exposure time 100 sec; corrected exposure +3 stop OR adjusted exposure
time 1200 sec
As was mentioned, I would get the initial exposure using a light meter (I
have a Pentax Spotmatic) and then applying the appropriate correction
factor.
I have no idea how Edward Weston calculated exposure for his negatives for
images like Green Pepper No. 30. The exposure was some hours at f/36.
Zack
On Sun, Feb 17, 2019 at 7:42 AM Janet Gable Cull <janetgcull@xxxxxxxxx>
wrote:
I have a beautiful print, received from perhaps the first print exchange
framed and hanging in my living room. I remember that it was shot at desk,
and required a very long exposure time. I've tried but am no longer able
to reach the photographer, Joel Alpers.
How do you calculate exposure time with the sun setting? I have a Minolta
IVF light meter.
Thanks for any help you can offer.
Janet Gable Cull
Sent from my iPhone
