Reciprocity failure with paper

Hi everyone,

Does anyone have information about reciprocity failure with paper. I
have to print large format prints which require long exposures (several
minutes) and can't open the lens without creating vignetting on teh
edges of the print.

It would help if I could know more about the appropriate correction
factor to use for exposure times of say 1 minute, then 2 minutes, then
3minutes and so on.

Thanks,

Guy
Received on Sun Dec 16 03:40:44 2001