Hi, I got the Ekos focuser working very well on my refractor but (a) that was a while ago, (b) I upgraded StellarMate and didn't manage to transfer all my settings, and (c) this is a new telescope and focuser setup anyway.

I'm running an AT8RC with a DIY direct-drive motor (PG27). The RC is 1625mm focal length and f/8, so the CFZ works out to about 65 microns. One step on the motor is about 2.2 microns.

From the days when I was trying to build a myFocuserPro, I recall the advice that your motor's step size should be no more than 1/10 of the CFZ if possible. But the step size the focus routine uses is something else again. Messing around pushing the buttons last night, it seemed that to be readily visible in HFR values (which were quite noisy), I needed to use a step size on the order of the entire CFZ!

So an initial step size of maybe 30, focus multiple 5? I'm using SEP detection, 1-Focus-Default profile, Linear 1-Pass, and a hyperbola curve fit per the docs (which are well in advance of the Focus module in StellarMate, but that's perfectly fine). I also poked in an AF Overscan of around 30, since I remember that's about what the old rig had for its backlash param in the driver (same motor, though pulley instead of direct-drive and rack & pinion instead of Crayford).

I suppose I could average one or more frames to get less jumpy HFR values. Would make this manual phase even more tedious, but once the AF is working it would be less of an issue.

Any suggestions gratefully accepted.

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