From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 04/26/00-05:35:18 AM Z
Jonathan Long wrote:
> ...
> What if you built a box with three different types of
> bulbs.
Likely there would be uniformity problems, especially if the coating
responds differently to the different bulbs.
> ...
> My second idea is to have the bulbs raised off the
> print a little. Say about 2 feet ...
It is a good idea to have room for dodging and burning, one foot can be
adequate. But it is important to have the tubes placed together close,
almost touching. Or if using U-shaped lamps, to have two layers offset
so as to minimized space between bulbs as viewed from the print
position.
> and have it in a box
> that has black sides to keep the source a little more
> specular. ...
Black box sides and bottom are OK, however the area around the lamps
should be painted flat white. Metal, foil, or a shinny surface may
produce non-uniformities at the exposure area. Flat white (as opposed
to black) helps diffuse the total light more. For this type of light
system, specular is not desirable, diffused is.
Also the exposure area should not be more than the area of the active
portions of the lamps as intensity fall-off may occur. Note that the
further the exposure area is from the lamps, the larger it can be
relative to the lamp area (to a point). Although moving further away
may allow exposing a larger area, it will take more time.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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