Determining exposure beyond.....................

Hi list!

Can anybody help me with how to determine exposure when correcting for
resiprosity failure when the measured esposuretime exceeds that of the table
from the filmvendor?

For instance when using Ilford HP5 Plus, the film data sheet gives the added
time for resiprosity failure until initial measured 35 secs(corrected for
pinhole f stop). How can I calculate the "correct" exposure time beyond this
point? Tiral and error until now has not been satisfactory for me.

Any help will be appreciated.

Rune
Norway

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Received on Mon Sep 17 12:06:10 2001