Sorry. Usually I reply to most messages on the board. Is it the same as a Hartman mask? If so, my answer is no. I focus on the pixel level by watching the FWHM numbers in my capture software getting the best possible focus on a dim star.
Perhaps you could enlighten me as to the focuser you are referring to.
Bill
-------------------- Bill Logan
Logan Observatory
Eagar, Arizona, USSA
Elevation: 7,400 feet (2,600 meters) ASL
NexStar 11 GPS on Milburn wedge
Permanent steel pier
12' x 12' Roll-off-roof
WO ZS-66ED refractor
Meade DSI Pro II monochrome
Meade DSI II OSC
Orion 7nm Narrowband filters
73 de WB9SAT
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