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Adjusting Backlash Settings

These instructions assume the procedure is done at mid-northern or southern latitudes.
It applies to Alt/Az and Equatorial mounts.  There are many ways to control the mount and access these settings, the Android/iOS Apps, website, SHC, ASCOM driver, etc.

  1. Sit an Equatorial mount with the RA axis pointing East or West instead of North or South as usual.  For Alt/Az mounts a normal setup is fine.
  2. Be sure the mount is well balanced on both axes (so the balance doesn't always fall to one side of the BL.)
  3. Point the telescope at Polaris and use a moderate power eyepiece (100x or so?.)
  4. Zero OnStep's backlash settings.
  5. Start tracking (to turn the motors on.)
  6. Stop tracking (motors still on.)
  7. Set a 0.5X guide rate, movement will be at 7.5 arc-seconds per second.
  8. Guide East until the Polaris appears to move.
  9. Press/hold West and start counting off the seconds.  Note the count when Polaris starts to move and multiply that by 7.5 for the RA/Dec backlash setting in arc-seconds.
  10. Point at Polaris again.
  11. Guide North until the Polaris appears to move.
  12. Press/hold South and start counting off the seconds.  Note the count when Polaris starts to move and multiply that by 7.5 for the Dec/Alt backlash setting in arc-seconds.
  13. Point at Polaris again.
  14. Set OnStep's backlash settings from above.
  15. Set a 0.25x guide rate.
  16. Alternately tap the East and West buttons a few times to confirm Polaris doesn't appear to move.
  17. If it doesn't move you can increase the BL slightly until it does.
  18. If it does move you can decrease the BL slightly until it doesn't.
  19. Alternately tap the North and South buttons a few times to confirm Polaris doesn't appear to move.
  20. If it doesn't move you can increase the BL slightly until it does.
  21. If it does move you can decrease the BL slightly until it doesn't.