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I've always used a separate guide scope and like the simplicity that it offers, but I now have pretty clear evidence of differential flexure despite doing everything imaginable to make a solid connection between the 2 scopes. So I want to try an off-axis guider and am looking for recommendations. I think it should be very adjustable (both rotation and prism position) to be able to find a good guide star. My current setup uses 2" SCT threads to connect the reducer/flattener to the scope. This could be changed to T threads, but I don't want to use a "nosepiece" or anything that is held in place with a thumbscrew. It is also possible to put an OAG between the reducer/flattener and the camera (using T threads) if the OAG body is 20mm or less. That might be preferrable, as it would provide a better match between imager and guider image scales. On the other hand, there is a larger image circle before the reducer, so putting the OAG there might make it easier to get good illumination on the guide star without obstructing the main image.
I have heard that OAGs often distort the star image and I'm concerned that that could degrade guiding accuracy.
So, what do you guys use and recommend? Thanks!