[Octane (Humayun)]

Hi all,

The following outlines my problem which I have also posted to the FocusMax User's Group on Yahoo! Groups.

The issue I'm having is that when I perform a Vcurve, the first best focus (centre) position is around the 2,000 mark (this number is not important, it's based on the step size, pause and duty cycle). On subsequent runs, the best focus position keeps shifting downwards, even though the draw tube is in the same position (as it should be). The focusing routine works (using AcquireStar), but, I'm just concerned about the fact that the best focus position number keeps changing. Once I reach a best focus position of 0, the software barfs because it thinks the focuser has no more inwards travel.

I have double-checked that my RoboFocus is secured tightly on the focuser shaft of the FSQ-106N and there's no slippage there.

My backlash setting is disabled in FocusMax and it was also disabled in the RoboFocus Control Program (have also tried enabling it with the default value of 20, as well as 40).

I even bought another RoboFocus unit, thinking it was the problem. Same issue.

I've also tried various step sizes, duty cycles and backlash settings. I make sure I start with a fresh profile after each configuration change. No joy.

The only thing I haven't tried so far is to use the new RoboFocus controller unit, with the new motor that I installed. That's easy done; I just need to swap the cables from the old unit into the new unit.

Does anyone have any magical fixes, or magical values that I should be inputting for the step size, pause, and duty cycle?

This is doing my head in. I wish to work towards a completely automated setup, and, focusing is the first step in a long list of things that need to be controlled.

To summarise: whether doing a Vcurve or a focus run (yielding HFDs of 1.4-1.6 on 4th magnitude stars), the best focus position number keeps trending downwards, eventually reaching 0.

Any suggestions?

H