Re: light table

Sandy King (sanking@hubcap.clemson.edu)
Wed, 27 Nov 1996 23:29:48 -0400

I don't know how you get them 1/8th inch apart, unless you're
>wiring the whole business yourself, with ballasts on the side, etc. and
>god bless you.

Exactly, with the ballast on the side or at either end, as work space
permits. To do this you fit the small bi-pole holders as close as possible
(minimum spacing determined on the size of your fingers, because you must
be able to
repalce the tubes.)
>
>However let me make certain observations:
>
>1. I have *NEVER* been able to get a noticeably uneven print, even at 1
>1/2 inches from the bulbs, at least by the method I devised to test,
>which was to coat a very large sheet of paper with cyanotype, sloshing it
>on so there was full saturation over the whole paper, then *underexposing*
>the print by about 60%. The rationale for that was that when you fully
>expose you tend to get d-max which could mask uneven exposure. Perhaps
>there is a flaw in my reasoning, or a better way, but I was satisfied.
>Then I moved the paper stage up 1 1/2 inches, for a paper-to-bulb distance
>of 3 inches, so evenness should be even evener.

If you are using tubes spaced 1 1/2" apart less than 5" from the printing
frame you are getting uneven result! These results may be visually
insignificant, but
they exist and would be measurable with approprite testing.
>
>2. Since my times were so fast with the bulbs spaced at average 1 inch
>(that was the reason I moved up), I saw no point in trying to get the
>bulbs closer.

This logic makes no sense to me. In basic enlaring in silver salt printing
I want to reduce exposure times to a minimum. The impact on my patience
quota between an expousre of 20 seconds and one of 5 minutes is very
*great*. The difference between an exposure of 2 minutes for carbon (with
1/8" spacing, bulbs 2" from printing frame), and 10-12 minutes (spacing 3/4
- 1 1/2", with bulbs 5-6" from printing frame) is really significant to my
working conditions.
>

>5. I said all this a couple of times (in the a-------). If my surmises are
>wrong, I wish someone would say.

Judy, what can I say? If you want to work with long exposures you have the
perfect working equipment to make it happen.

Regards,

Sandy
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