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Before you start measuring the focuser's backlash make sure that you have disabled all features that can cause unwanted motor movements. Disable the backlash compensation, temperature compensation, final inward move in
Scope & Focuser settings tab. Also the backlash compensation in the ASCOM /
INDIGO / INDI driver settings.
Here are some ideas how to measure the backlash.
Make sure that you have determined the right
Focuser Move Step. Focus by eye as good as you can, select the option
Calc Backlash and click on
Run button. The result will be printed in the
Log Panel. Make sure that the scope is well tempered. Use night with stable atmosphere and star or area well above the horizon.
II. Via manual measurement
1. Focus via
Bahtinov Aid. Make sure that you are moving with very small steps and in same direction. Let take that you are moving in "Out" direction. Records the focuser position P1 where the focus is best.
2. Move in "Out" direction with big step - 1000 (or even more if you think that you have big backlash)
3. Move in "In" direction with same step - 1000
4. Start moving with very small step in "In" direction till you reach the best focus. Record the focuser position P2
5. The backlash is B = P2 - P1.
It is very important that you don't change the direction in the points 1,2. After that you have to start moving only in opposite direction for points 3,4. Here again is very advisable to make sure that the scope is well tempered, to use night with stable atmosphere and star well above the horizon.
Similar measurement could be made using
FocusCraft and
Focusing Aid but is harder as there is no easy to see confirmation which is the best focus point.
The
Backlash Aid has some experimental approaches to measure the backlash. The feedback for them is a "mixed" bag - they work for some users and doesn't for other. However they can give at least idea for the magnitude of the backlash.
