Getting the autofocus to run reliably with my short focal length AT65 was easy and it works every time. Not so when trying to image with my SCT. Can anyone give me some ideas how to get it work reliably?
It’s an 8" EdgeHD SCT with .7 reducer so focal length is 1422 mm. Camera is a Canon T2i DSLR. Focuser is a Rigel System. SGP is newest beta of 2.4.
Last night I did the initial focus with a Bahtinov mask. I have steps at 120. That resulted in a focus curve that was close to what the mask got but the curve HFR values went from a maximum of 6.5-7 to a minimum of 5.2 at the bottom of the curve. If I set step size higher, the stars go so out of focus that SGP doesn’t detect them anymore and the values drop very low. If I lower the step size, I get more or less a flat line.
AF sample size is set to 100 and nebula rejection is towards the weak side but I have moved it all over and it doesn’t seem to change anything.
I have noticed that SGP 2.4 seems to detect less hot pixels when the stars are out of focus but I also notice that it is using very few stars overall, maybe 20 are boxed in the image (I didn’t actually count but it is not close to 100 as AF sample size would suggest). It still has problems with the stars as they move farther out of focus. When I got up this morning all of my later images were so out of focus that the stars were big dim circles. It was in focus when I started.
Maybe I’ll have to just use temp compensation like I do with the Ha filter? I don’t have FocusMax or other software to try.
Thanks for any help,