Focus mode with Bin 1, not zoomed with the magnifying glass in the upper left, works for me. I can have it refresh every second or so. I am using a dedicated astro cam. Then, when I feel like I have it focused, I switch to Preview mode and take a ten second exposure and click "Detect Star". That shows the average star size to help confirm that the focus is good. The best way is to use an automatic electronic focuser, which I have on order now.