APUG - View Single Post - Reciprocity Formula - Tri-X 320

Maris · 10-03-2007, 11:22 PM

Try this:

Take the measured time and multiply it by 7.5 then

raise this product to the power 1.42 then

divide the result by 10.

This should be very close to the correct exposure time.

If tonal matching over a range of reciprocity influenced exposures is required then development compensation is called for.

I don't compensate development because I like the reciprocity induced contrast increase (John Sexton's "Quiet Light" theory) for dimly lit landscapes.

10-03-2007, 11:22 PM	#4 (permalink)
Maris Join Date: Jan 2006 Location: Noosa, Queensland, Australia. Posts: 193	Try this: Take the measured time and multiply it by 7.5 then raise this product to the power 1.42 then divide the result by 10. This should be very close to the correct exposure time. If tonal matching over a range of reciprocity influenced exposures is required then development compensation is called for. I don't compensate development because I like the reciprocity induced contrast increase (John Sexton's "Quiet Light" theory) for dimly lit landscapes. __________________ Photography, the word itself, invented and defined by its author Sir John.F.W.Herschel, 14 March 1839 at the Royal Society, Somerset House, London. Quote "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..". unquote.