Re: Step wedges

Judy Seigel (jseigel@panix.com)
Fri, 22 May 1998 22:29:46 -0400 (EDT)

On Fri, 22 May 1998, Tom Ferguson wrote:
>..... I made
> a simple version of Phil Davis's spot meter/densitometer. Basically a spot
> meter with closeup diopler filters. Now I can match negative densities to
> step wedge densities very accurately and quickly.

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