Tom, is that a misprint, or is there such a thing as a diopler filter?
Either way, could you possibly give a few more details, so maybe people
who are less intuitive about this than you could do it?
Someone else once told me that they used Phil Davis's method for making a
densitometer out of a spotmeter... but I never could could visualize the
drill... I suppose if it's easily made back into a spotmeter, the saving
would be consierable... or even if not. Is it accurate?
Judy