[alt-photo] Re: Ultra Long Exposure Reciprocity Failure?
Loris Medici
mail at loris.medici.name
Fri Jan 20 08:59:34 GMT 2012
Geoff, from now on I'll switch to your formula below; it gives
slightly more exposure than T^1.48 (negligible), but I would
definitely prefer to err towards overexposure than underexposure...
See some comparisons below:
30 secs., T^1.48 = 153 secs., T x sqrt(T) = 164 secs. (diff. in stops = 1 / 10)
60 secs., T^1.48 = 428 secs., T x sqrt(T) = 465 secs. (diff. in stops
~= 1 / 10+)
120 secs., T^1.48 = 1195 secs., T x sqrt(T) = 1315 secs. (diff. in
stops ~= 1 / 7)
Thanks for sharing!
2012/1/20 Geoff Chaplin <geoff at geoffgallery.net>:
> If t is the metered time in seconds the t x root(t) works for FP4+ and Adox
> up to a couple of hours or so (t = 400 sec or so).
More information about the Alt-photo-process-list
mailing list