This is the best image I've seen yet to demonstrate a focusing technique. Thanks for posting! I use Nebulosity 2's HFR technique which works very well too. One of the nice things of quantified focusing is that you can chart it to see trends.
How does this mask deal with seeing? Does the central line shift as seeing changes? That would be a terrific benefit of this mask if it's seeing independent.
-------------------- Best,
Sander
C11-HyperStar on Atlas EQ-Q driven by EQMOD
William Optics M110 With FR-III/TRF-2008
DS2090 guide scope
QHY-8, DSI-Pro and DSI cameras
watec 802h video camera with KIWI OSD