Quote:
Originally Posted by stephen2615
Thank for the response.
I have the correct back focus for both cameras. I have to have 55 mm.
The 16200A CFW7 with the OAG M = 55 mm (54.5 to 55.5 mm from QHY). I have to screw the OAG directly onto the flattener/reducer. A filter in the filterwheel should give me about one mm gain in the back focus. I measured the distance from the 16200A filter wheel cover plate and because of the thread distance on the reducer, my back focus distance is 56.7 mm. I think with the filter, it takes it down to about 56 so it is one mm too long. I am pretty sure that one mm out with back focus is not going to stop the camera from focusing.
The 163C has 55 mm back focus by way of spacers and the OAG. So both have (almost) the correct back focus.
As far as the focuser goes, 92,000 has a huge blob of Acrux, while 100 has a moon sized blob of Acrux. The focuser travel distance is about 90 mm.
I am somewhat gobsmacked at this problem.
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Sorry, I was thinking of that the wrong way, pure focus not corrector spacing. To get the right spacing to your corrector you should need approx 25mm less spacer between the camera and the corrector with the 16200 than the 163. Aside from the OAG, how much spacer do you have between the OAG and the 163? If you get the reducer to sensor distance the same between both cameras the focus point should be the same. I know they can be pretty touchy, fiddling around with spacing increments when setting up my old ED272, 1mm spacing corrector to sensor change made a much bigger difference to the focuser travel. COmparing the two cameras, it is possble the 163 was not quite at the ideal spacing, the abberations will show up in the corners first and the APS-H sensor of the 16200 will show them up with a smaller spacing discrepancy than the 4/3.
How does the corrector attach to the drawtube? If it is a lack of "out" travel can you add a spacer there?