From: Edward Meyers (aghalide@panix.com)
Date: 05/05/00-05:37:30 AM Z
Two questions...Doesn't the inverse square rule only apply with a bare
light bulb, without a lens focusing the light?
And...UV is radiation, not light. Light is the visible part of the
spectrum. So shouldn't UV light be an incorrect description? Another Ed.
On Fri, 5 May 2000, Ed Stander wrote:
> Dear all:
> I have a saltzman 8x10 enlarger with a 240 el-nikkor lens and a 1500
> watt Olec graphic arts UV light source. The light source has a built in
> integrator, but I use a photocell on the easel for printing. The olec also
> has a very large fan built-in so the negative doesn't fry. The lens + film
> train removes approximately 40% of the UV light from the beam according to
> my UV meter. Thus my exposures start with the equivalent of a 900 watt bulb
> located at lens height. From there, the inverse square law applies. I can
> print gum enlargements with this set-up using a 10 minute exposure.
> Some lens companies make quartz glass enlarging lenses. I remember seeing
> one on Glenn Evan's web page some time ago. These lenses would decrease the
> exposure time substantially, since quartz does not absorb UV the way other
> glasses do.
> CHeers, Ed
>
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