I’ve been using the auto focus feature for some time now with what I though was good results, but while processing recent data I discovered that while the SGP focus with my Ha filter was pretty spot on, Oiii and Sii are off a bit. I checked last night that SGP is re-checking focus on filter changes as intended, only it seems to be coming up with nearly identical focus points for all three filters. When I manually checked focus for each filter with a B-mask, I got a result pretty close to SGP’s for Ha, but off >100 steps for the other NB filters. I see pretty noticeable double star spikes in processed images with SGP focus for Oiii and Sii and single sharp spikes for Ha images. When I use my B-mask settings, I got pretty good spikes for all three filters - and this with setting the focus at the beginning of the evening. I used the same exposures for FF and the B-mask, though FF bins 4x and the manual “take one” exposures were 1x. Is the problem due to binning?
Larry