Originally Posted by Stephen Benskin
My Stouffer chart is back-lit with doubly diffused light.
Shooting with a 50mm macro lens onto 35mm film got corner-falloff, creating dips in the curves.
Switching to a 135mm lens with an extension tube, stopped down 1.5 stops, solved the problem.
FP4+ and HP5+ now have straight line curves from centre to edge back to centre of the Stouffer.
Also, I shoot the upper and lower halves of the Stouffer chart in separate exposures, so that each shot only has a 5-stop range instead of 10-stops. This almost eliminates flare that would otherwise push up the toe-area.
The result of all this is almost as good as contacting.