Columnated? or collimated light
SCHRAMMR@WLSVAX.WVNET.EDU
Fri, 28 Feb 1997 09:00:54 -0500 (EST)
There is a physicist out here and I are one. I think you folks are
talking about COLLIMATED light. There is an optical device called a
"collimater" which renders light into parallel rays. This is the purpose
of the condenser lenses in a condenser enlarger. If you put the light
source at the focal point of a lens, the light rays emerging from the
lens will be parallel or nearly so. Also, the further away you are from
a light source, the more it acts like a point source and the more nearly
parallel will be the light rays reaching you. Finally, without getting into
a discussion of diffraction effects, the closer your light source is
to a point source, the sharper your prints will be. Opinion: I'm not sure
I would go to a lot of effort to try to achieve a point source. Judy has
noted that she could notice a difference when using a hand lens, but most
folks (normal people, not alt-process printers) don't go around examining
prints with a hand lens. However, I confess to having some thoughts about
using a mercury vapor street light (bare bulb) for printing. Its on my
long list of things to do after retirement.
Bob Schramm