The topic says it all. I have acquired an ASI120MM-S recently, and although I am happy with the camera monochrome imaging is a little new to me. I have googled the subject but all I could came up with is a formula of finding the dept of focus, not exactly what I was looking for. I read it somewhere that different colors of the spectrum has different focus point. I think it said that blue is the one to watch for in that matter.
I use a C9.25 with the camera and usually shoot aroung F20.
Do you guys refocus for each filter? If yes, what is your technique?