Originally Posted by Chan Tran
Use a densitometer or spectrophotometer to check it out if it's really 18% gray.
I possess neither of these fine tools, but I do have negatives that are exposed to my expectations, so I would guess that it must be close enough to serve the purpose.
Tom, on Point Pelee, Canada
Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there...