Thanks for all your "help". Maybe I can repay the favor someday.
Thanks for all your "help". Maybe I can repay the favor someday.
switch to a cold light or led bulbs, then heat is a non issue.
Continuing this sad saga, I've used my CB7 with a point light source. The lens is always used WIDE open, but that has no impact on heat -- just the time the bulb is ON. And it is VERY hot. It has fried a couple of Kodak test Step wedges in no time at all. This puppy needs extremely short exposures for a typical negative -- which is a problem. Sure, I can add ND filters, but then the negative gets fried with the longer exposure time.
The heat absorbing glass has never cracked. The condenser cells have never cracked -- despite long exposure to the point light source.
ALL of this is with the heat absorbing glass in place. My thought was that an additional heat absorbing glass would help. It probably won't help, but I'm not expecting much from this Forum either. Any non-dismissive responses would be appreciated.
I have one factory installed, and one not. Both sides looks exactly the same to me. If it's my lucky day, you can inform me of the difference.
A second heat absorbing glass with a spacer to keep it from touching the first glass could help.
The basic principle of the heat absorbing glass strategy is that the glass absorbs infrared on one side from the lamp. The glass then becomes very hot and re-radiates the heat energy in all directions. In effect the glass sends half the heat energy back towards the lamp and the other half toward the condensers and the negative. A second heat absorbing glass could reduce the heat load by half again. Heat absorbing glasses have been known to shatter under stress if mounted with no room for thermal expansion. The traditional heat absorber is greenish high iron content glass and a second glass could introduce a significant (?) colour change in the enlarger beam.
Photography:first utterance. Sir John Herschel, 14 March 1839 at the Royal Society. "...Photography or the application of the Chemical rays of light to the purpose of pictorial representation,..".
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