Re: Spotmeter densitometer
Jadlupp (Jadlupp@aol.com)
Sat, 23 May 1998 22:11:27 -0400 (EDT)
I built the Davis-Pentax desitomiter sever years ago, and bought the close up
lens from Edmund Scientific, used a paper punch to make the 1/4-inch or so
hole in a black construction paper mask. I found the Pentax is sensitive to an
area twice the diameter of the 1-degree circle (probably due to flare). I
calibrated my meter against a calibrated step wedge, and found the system to
be linear between a meter reading of 3 and 11. For use, I set my light source
to read 11 with no negative (or print for reflectance), and then my densities
are 3.0-(meter reading times .2818).
This is close enough for paper calibrating and negative development curve
work. Like an earlier post, the error is less than 1/6 of a stop.
Don