I have this Meade ETX attached to my a65 and focusing is really difficult using only the knob on the scope. The tube (purchased from Meade) is made in 2 pieces that thread together. There is approximately 5mm of "adjustment" - do you think I can use this as additional focus?
May 6, 2023
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I have no experience with those specific parts but sounds like you are contemplating a loose and incomplete securing of parts that are only meant to be a snug fit. Be aware that threaded pieces are nearly always designed to have enough clearance to be easily assembled, but not to have any particularly good alignment in the partially assembled state.
The bottom line on that is that there may be a lot of sag. If you focused in the center of the frame one frame edge would be front focused and the opposite would be back focused. The only way to have the sensor be securely held perpendicular to the optical axis would be to fully thread the pieces together in order to get their mating flat surfaces to engage.
There might not be many aftermarket focuser accessories available for that small class of telescopes, but larger Schmidt-Cassegrains are well served and might point the way toward a possibility: do a search for Crayford focusers that might fit your scope.
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I didn't test the slop in the threads and as you replied - there is quite a bit.
I don't understand why this T-adapter was made in 2 pieces.
