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Old 19-05-2018, 10:02 AM
Billyboy78 (Bill)
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Billyboy78 is offline
Join Date: May 2018
Location: CRESTMEAD Brisbane
Posts: 103
Originally Posted by Wavytone View Post

The Nasmyth idea is good, and on that size I expect you would be riding as a passenger on the mount and using electric slewing. The focal length of a 20" will be of the order of 6-7 metres which poses a significant challenge however ... I found non-tracking altaz mounts infuriating to use with a mak of focal length of just 2700mm, so at 6000-7000mm the problem just gets worse and you will have to make this track and probably GOTO just to be useable.
Wow, let me clarify some points.

Primary :500mm F5 FL :2500mm.
Secondary : 200mm F4.5 FL : p 920mm x p' 3990mm
Standard german equatorial mount with 75mm shafts, 5mm wall thickness.
viewing angle : 27deg

Yes I've done ray tracing.....on my lounge room floor using pieces of cotton.
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