Addendum - EAF Focuser |
EAF Backslash Compensation |
updated: 2024-05-30 |
Definition
Backslash is a type of idling after a change of direction and occurs in most gearboxes. The backslash is caused, for example, by slight gaps between the teeth of the two gears. In the event of a change of direction, the dead angle must first be overcome within the gearbox before the change of direction becomes effective.
There is also a small gearbox in the EAF motor drive as well in the focuser, both generating a tolerance-related backslash.
Procedure
Step |
Action |
1 |
Move the focuser from the innermost position outward e.g. to step position 1000, so that the focuser is fully engaged |
2 |
Mark the fine focus knob with a little dot |
3 |
on the ASIAIR App goto EAF Settings and set the coarse steps to 200 and the fine steps to 10 |
4 |
Example: EAF on TS-Optics 2.5" Rack and Pinion Focuser (TSFOCR25): it took 27 fine steps until the focuser knob started moving |
5 |
Multiply the number of fine steps by the number of steps per fine step to get the backslash |
6 |
Enter the backslash result n(in this case limited to the max. value of 255) in to the ASIAIR app and you are done. |
7 |
To determine even more precise backslash values, you can reduce the Fine Step value to 5 or less, for example, and then use this value. |
Tutorial: Calculate and Adjust Backlash on a ZWO EAF with the ASIAir (youtube.com)
Optical Configuration |
Measured EAF Backslash |
EAF on TSO 2.5" Rack & Pinion Focuser |
~270 (max. allowed input in ASIAIR App is 255!) |
EAF on M90 TS600 Rack + Pinion (TSO APO 90/600) |
20 |
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