Re: PHOTO-3D digest 1196

[bobh@xxxxxxxxxxxxx (Bob Howard)]

RE: Gary C, Why the black top on projection bulbs (or a metal black
cap)?

It certainly won't hurt the bulb not to have it. The reason for the
black cap or top is so simple that it isn't thought of looking at the
bulb. Most projectors are used in a dark room and the lamp house has
ventilator louvers or baffles on top. Having the top of the lamp black
or capped minimizes the light going UP to the ventilator and thus into
the darkened room..so it is part of the minimal "light proofing". An
enlarger in a darkroom has to have a good system as it is a projector
too, but can't "spill" any white light. BobH


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