I own a Televue TV127is. I've had it for about 8 years now and I really like it. Recently I decided that this summer I wanted to get a wider FOV. So, I got the .8 focal reducer for the scope. I read the instructions which said that the back focus is 55 mm. I have an ASI1600 camera, ZWO 7 position filter wheel, and ZWO OAG. Total back focus is 42.5 mm. I put 13 mm of spacers on between the wheel and the camera to get me to 55. Terrible results. I called Televue and they said 58.5. So, I switched to 13 mm of of spacers and still got terrible stars.They look like comets in the corners. I extended it out another 3 mm but no that made no improvement.
So, I'm asking if anyone has the same scope and focal reducer and has used it with a CCD camera/wheel/OAG and gotten good results. If so, what was your spacing. Televue also said that if I'm using 3 mm filters (which I am) that I needed to add one additional millimeter of spacing to make it perfect. From what I can see, I'm not even close. I had a friend with me doing this so either both of us cannot use calipers or we never got the right spacing.
Here's a corner ----