Re: [ATM] Small Dob Question: Alignment features needed for accurate encoder GOTO's?

["Mel Bartels" <mbartels@bbastrodesigns.com>]

For your specs, 1/32 inch tolerance can result in an error up to 7-8
arcminutes, which is satisfactory for the tasks you want to do with the
scope.  A real silent killer is the optical to mechanical axis match.  Try
to get them to coincide as much as possible - that includes the offsetting
if you're going to do any.

 

Mel Bartels

 

 

For the encooders and interface, I was considering using  David Ek's DIY
interface including the recommended US Digital S1 or S2 encoders (4000 to
10000 tic encoders recommended?) or possibly purchase a Nova MG5 interface.
Have also considered going ahead and getting 

 


Now, for my "stab" at the performance parameters.  Ideally I would like the
GOTO accuracy to place any selected object within the FOV of a 24mm Panoptic
eyepiece for an 8" f6 Dob.  And of course 100% success rate would be great.
But I suspect that's not realistic for the average "wooden" Dob mount?  So
an acceptable compromise (which I hope is not unrealistic?) might be 95%
successful positioning within 75% off-center of any object located within 90
degrees of the last DSC sync/calibration? 

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