Doug S replied to the topic 'Question about focuser module' in the forum. 1 month ago

The learning curve is part of the fun... It will be over quite soon enough. If confused, just ask (lots of folks are willing to provide help when you need it).

About backlash, simply put, this is just some mechanical slop in the gear mesh of your focuser motor. It's normal. The effect of backlash is that when your focus motor reverses direction, some amount of steps are required before that slop is taken up and the motor actually causes shaft motion. You can eyeball this by carefully watching your coupler's set screw or anything else (as close to the motor shaft as possible) that moves as you push focus-in or focus-out controls.

The test is pretty simple. To set up for the test, move one direction with a reasonably small jog until you know you're causing motion in that direction. Once you know you have motion in that direction, you're ready to begin the test. Using something like 20 steps (progressively refining as you start to learn what the real value is), jog focus in the REVERSE direction. Keep jogging IN THAT DIRECTION, noting total steps as you go. When you first detect motion, the total number of counts it took is your backlash value. Repeat the same test now in reverse again (the other way). Do those tests repeatedly (both directions) until you convince yourself you have the smallest number of steps required to cause focuser motor shaft motion in either direction. That's the number you want to set in the Ekos/Indi backlash value. FWIW, my EAF motor has 95 steps of backlash. An educated guess might be that you're looking for something on the order of 25 < backlash < 100? Hope this helps. Good luck...

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