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The focal length of an 18" f/4.5 mirror

Started by [email protected], 10/05/2002 12:36PM
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Posted 10/05/2002 12:36PM Opening Post
Bob Polcyn
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Location: Hot Springs SD, US

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I can roughly estimate its focal length from the mirror to focusser distance but would like to know the mathematics involved. Is there a math oriented user out there who can help?
Thanks.

Bob Polcyn
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Posted 10/05/2002 01:49PM #1
Bill Byrd
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18 X 4.5 = 81"
Bill
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Posted 10/05/2002 05:32PM #2
Bob Polcyn
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Thanks all for the quick responses. The info definitely helps.

Bob Polcyn
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