Jan Pietrzak wrote:
> Wattage is exposure time.
More accurate is wattage per length of tube. Technically it should be
area, however the length is typically much larger and the widths about
the same. When comparing lamps of dramatically different widths, the
area should be used.
A 20W 24" tube will produce about the same print exposure as a 40W 48"
tube (if same type and close to the same width).
Also keep in mind to use a flat white reflective surface. Mirror like
reflectors can cause hot spots. Exposing a large coating for a middle
gray without a negative can be used to confirm uniformity at the
printing location. If there are hot spots the print can be moved
several times during exposure, but it is better to start with a uniform
illumination. Keep in mind that moving closer to the lamps may result
in hot spots.
It is best to build the light source area about the size of your largest
expected print. Also lamps may be switched so as to only use a few
bulbs for smaller prints. However some bulb types may diminish in
output over their lifetime causing this area to be weaker when exposing
larger prints. Best to have a bulb assortment for each size (ie: one
setup for small, another setup for large.)
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/Received on Tue Dec 21 13:21:28 2004
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