View Full Version : Reciprocity correction for Arista.edu 100

Gary L. Quay
21-Jan-2006, 09:00
I need some info on Arista films. I can't find it on the Freestyle site. I need a reprocity correction chart for the Arista.edu Ultra 100 film. Freestyle has charts for the Arista.edu, but not the Ultra. It is made in the Czech Republic, so I'm guessing it's repackaged Foma, but I'm not sure. Anyone know?

Secondly, does one have to adjust development times for the increased exposure?

Thanks bunches!


Donald Qualls
21-Jan-2006, 12:32
Yes, Arista.edu Ultra 100 is the same as Fomapan 100. It has the same reciprocity failure curve as Plus-X or Tri-X, near enough.

Most film manufacturers recommend reduced development as you start to pile on reciprocity correction, but my experience has been that this is necessary only with high contrast subjects (like night scenes that include both well lit and poorly lit areas, where detail needs to be preserved in both) -- which would require reduced development in normal lighting as well. Yes, reciprocity failure does increase contrast, but my experience has been that it doesn't do so enough to require a bunch of adjustment at reasonable exposure times (say, under a few minutes).

If you aren't adjusting development times, for conventional films like Plus-X and Fomapan 100, it's generally sufficient to triple, rather than double exposure time for each stop past one second (though Ilford's charts show slightly less correction is needed for Pan F+, FP4+ and HP5+). I've used that calculation a lot with Tri-X and APX 400 and gotten very good pinhole negatives with exposure times ranging from a few seconds to more than an hour...

Gary L. Quay
22-Jan-2006, 09:00
Wow! That was exactly the info I was looking for. And, from a person whose last name also starts with 'Q.' Who'd a thunk it. I do a lot of night photography, some of it high contrast, some not. I am a self-taught photographer and only recently a proud ower of my very own darkroom. Until yesterday, I had never heard of reciprocity correction in B&W films. I knew about recoprocity failure in color films. I've always bracketed my night exposures (and day shots, too, but not by as much), so I've always gotten usable negatives, but I've recently made the jump to large format, and bracketing is a tad more expensive than the medium format I normally use.

Thank you for the information!