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Re: Secondary Mirror Size

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Posted by Walter Hamler on January 25, 2001 21:12:48 UTC

I plugged the numbers into my copy of NEWT 2.5 and came up with the following: With a 1.5" the 100% illuminated area will be 0.14" dia. and the 75% illum area will be 0.88". This would be acceptable for 1.25" eyepieces and lunar/planetary work.
Moving up to the 1.83" would give 0.54 and 1.25" respectively, but would necessitate a 2" focuser to prevent vignetting. The contrast difference would not be noticible I would think. Personally I'd go for the 2" focuser and the 1.83" secondary.

Walt Hamler

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