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Topic: Cheap Flat Plastic Fresnel Lenses

Bill Enos
Film God

Posts: 2081
From: Richmond, Virginia, USA
Registered: Apr 2000

posted 08-02-2002 10:34 PM

With carbons in unreliable supply and quality we relamped our Brenograph with FX750 projection bulbs. We knew the light output would be much lower but it turned out a lot lower than wer figured. The problem was the arc produced so much light that it was bright even though the surface of the rear condenser was extremely pitted from many years of arc striking with the douser open. (I've been told that the guys in the 30s and 40s really hated this machine and did this to get even with management for using it). We experimented with a lot of things and ended up removing the damaged condenser and left the other of the pair in place. The damaged condenser was replaced with one of those flat plastic flexible magnifier sheets that can be bought at bookstores, and office suppliers for about $2.50. Cut with scissors to get it centered, it was placed ahead of the remaining glass condenser. It worked perfectly a d raised the light level to nearly the same as the arc put on the screen thru the bad lens. For two bucks it replaced a lens that would have cost $50 or more if it could be found. Try one of them if you have a similar need. Just be careful to center it.

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 08-02-2002 10:41 PM

Bill, would it be possable to post some pictures of this so everyone can see what you have done. Thanks

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Kenneth Wuepper
Phenomenal Film Handler

Posts: 1026
From: Saginaw, MI, USA
Registered: Feb 2002

posted 08-03-2002 06:32 AM

Hello, Bill,

I am pleased that you have found a way to keep that vintage piece of gear in operation. It is important to preserve the heritage of the theatre. There will be no more Brenographs made but I am sure that there will be slide projectors of some type made for a long time.

I have been a fan of the "Byrd Theatre" ever since my Hi Fi Stereo days when I got the wonderful recording of Dick Liebert on the Richmond Byrd WurliTzer organ. The disc is called "Liebert Takes Richmond". It was also available in the new format of 1/4 inch two track stereo tape!

Great Job,
KEN

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