I have used APPM successfully with my Mach2 and 130mm Starfire GTX. I am now trying to build a model for my 1100 with a CFF 300 on it. I have some specific questions about image scale. I'm using USNO A2.0.
The camera is a ASI1600MC-Cool with a 0.67 focal reducer on a 300mm f/15 Cassegrain. I calculate unbinned image scale at just under 0.26, which is of course pretty small. I binned 2x2. My initial run was not successful -- many failures, often reported as due to potential image scale issues. Later, using the image-link-test solve capabilities, I was able to get a couple of the earlier images to solve, but the estimated image scale in those calculations was reported just over 1.0. When I re-ran the image-link-test solving with that 1.0 entered for image scale I got about half the images to solve easily.
Question #1: Is this inconsistency because of the 2x2 binning? Does the plate-solve results in the Image-Link-Test display estimated unbinned or binned image scale? The math works: 4 x 0.26 is about what was reported.
Question #2: Just to confirm, then, that when I enter X-scale and Y-scale factors in the platesolve setup, I should enter the unbinned values, right (0.26)? The software will then adjust, I assume, for the binning.
Question #3: What options should I play with to reduce the potential for failed solutions due to image scale issues. How high can I set (realistically) the Image Scale Tolerance? Is 50% too high? 100%? I also assume it would be helpful to set Catalog Expansion to a higher value, maybe to the max at 0.8. I'n not trying to get fast solutions, just more solutions.
Question #4: Any other suggestions for running APPM with such a small image scale? I was worried about getting enough stars so I increased the exposure time on the camera (from 5 to 15) and reduced the sigma above mean (from 4 to 3). Anything else?