Hello Niko,
Ever since I have been in this hobby a friend put me onto this program called Focusassist and I think that this is the website.
http://jstanley.pingerthinger.com/focusassist/
I also downloaded a magnifyer program that allows me to zoom in. The focus assist allows you to take an image at different ISO and times and then downloads the image to the screen of the program. So you can see the stars and then I move my magnifyer program over a selected star ( i have the zoom set to about 8x and look at the focus of the star. If it looks fuzzy I adjust the focus, keep the magnifyer there and shoot again and the new image downloads and I can see if the adjustment was OK and then I keep going until the star will basically resolved to like a single pixel or close enough. I have done this for ever and it is very easy but have not used a batinov mask at all so can not compare.
Mark