U of S | Mailing List Archive | alt-photo-process-l | RE: intensity of bulbs

RE: intensity of bulbs

The length of the tubes is primarily determined by the maximum size of the
print you wish to make - plus a margin to avoid light fall-off at the ends.
I use 24" tubes to print 20" negs without a problem.

At the same distance from the tubes the light intensity is proportional to
the power of the tube (assuming the same type, efficiency etc). So a 40w
tube would be twice as bright as the 20w tube.

Geoff Chaplin
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-----Original Message-----
From: Barry Singer [mailto:bsinger@sasktel.net] 
Sent: 24 February 2009 07:18
To: alt-photo-process-l@usask.ca
Subject: intensity of bulbs

A cursory search of the archives doesn't help me answer this question.  
Perhaps some one can help?

Does a 24" bulb at 20 watts have the same intensity as a 48" bulb at 40