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Hubble optics any info

Started by kenkolen, 01/16/2012 05:30PM
Posted 01/16/2012 05:30PM Opening Post
Looking for anyone with experience with Hubble Optics. I was interested in putting something together for a Equitorial Mount, they have a dovetail option for their 14".
Posted 01/29/2014 01:57AM | Edited 01/29/2014 03:24AM #1
A fixed dovetail mounting on a GEM Newt reflector will result in some precarious (if observer is on a ladder) or at least uncomfortable eyepiece positions (typically with fixed mounting the eyepiece axis is parallel to the Declination axis and opposite the Declination counterweight for all-sky usage). Far better are clamping rings around the tube or mirror cage which allow repositioning (by rotating around the optical axis) the eyepiece orientation with respect to where the scope is pointing. If an open-truss tube is used with a dovetail-mounted mirror cage, then a fully-rotating upper cage is required for varying eyepiece orientation (this method requires great precision in upper cage to tube construction to retain collimation per object to object). My own 6" f/8, 8" f/7, 10" f/4.5 & 12" f/5 reflectors are all GEM mounted with rotating clamp rings which provide for comfortably prolonged observations and can readily accomodate all ages (heights) of viewers. The one exception I can think of & pertains to your larger aperture, is that a fixed focuser mounting which aligned downwards in the same direction as a GEM's declination shaft counter weight shouldn't be too high off the ground for most observing from the Northern hemisphere; except at the Zenith or near the horizon, you'd always be tilting your head backwards & looking slightly upwards into the eyepiece with such an arangement.