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Old 08-06-2010, 10:24 AM
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allan gould
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Join Date: May 2005
Location: Brisbane
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Mike
I think that some of your distances are incorrect as Ive been verifying my Meade f6.3 FR and can state that the correct distance for this is 87mm from chip to back element of lens. See http://timosastro.1g.fi/tools/focalreducer.html
This FR works from 80-106mm with acceptable results. Best is at 87mm. Ive confirmed this and have seen the distance at some sites quoted as 106mm.
The spacing for the f3.3 remains the same at 57mm.
Also the GSO 2" Coma Corrector cant have a spacing of 53mm as it comes with a 2" adapter which is already at 42mm from the back element and a T adapter on a Canon camera would add another ~45mm to the chip. Just measured it on the one I purchased from Andrews. (edit - you're right as I miss read FR for coma corrector).
Also note that the GSO and AstroTech Coma Corrector are not the same beast - many are assuming they are.

Last edited by allan gould; 08-06-2010 at 10:34 AM.
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