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Re: The best catadioptric telescope

Started by tomdisco, 05/29/2003 06:24PM
Posted 05/29/2003 06:24PM Opening Post
Alex has asked how you lock down the C9.25 primary. In addition to that information which Feather Touch Focuser is appropriate for the 9.25? They have 1.5", 2.0", and 2.5" travel options. Should one just get the 2" option to cover all possible focusing situations or is that overkill?
Posted 05/30/2003 12:04PM #1
Seems to me you can get by with very limited focuser travel. At most you would want the difference between your shortest and longest focusing eyepiece. Point is, you move you main mirror to wherever it looks like it is in focus, then lock down the mirror (if you ever figure out how to do that) and then you only need a little travel to bring everything to perfect focus.

Alex
Posted 06/01/2003 01:47PM #2
Steve,

I just read a Cloudy Nights review of the Williams Optics SCT Crayford Focuser ($149.) by Rod Mollise. With that one apparently you do not "lock down" the primary. You simply use the regular focuser to bring your object to near focus and then use the Crayford thereafter. This may be the normal procedure for the Feather Touch Focuser as well. Also, aside from being a lot less expensive, the WO SCT Crayford does not require an SCT base adapter. It simply threads onto the existing back and is rotatable.