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LONG focus lens???

Started by plunkett, 05/04/2004 02:47PM
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Posted 05/04/2004 02:47PM Opening Post
Pat Plunkett
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Join Date: Jul 2001

Location: Wheeling WV, US

Posts: 115

Does anyone know a source for refractor lenses with LONG focal lengths? My club uses a ~5" lens and a diagonal mirror to project a solar image which is in focus about 50 feet away. I guess this would be about an f/120...

Pat
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Posted 05/04/2004 03:38PM #1
Russ Schnitzer
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Join Date: Mar 2004

Location: Prescott AZ, US

Posts: 36

Take a look at D&G Optical. They offer very long f ratio lenses should you desire. They also have a reputation for quality.
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Posted 05/05/2004 01:21AM #2
Pat Plunkett
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Location: Wheeling WV, US

Posts: 115

Dan,

The beauty of the moveable mirror, stationary lens is that you can "launch and leave" it for a while whereas the ep projection method requires constant attention. We were able to leave our setup for about 10 minutes at a time while projecting onto a building with some poster board attached. It's actually quite cool!!! Also, I've "smoked" eyepieces in the past using projection.

Pat

Pat
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