User defined number of runs for AutoFocus

Sequence Generator Feature Requests
1

It would be nice to have the ability to set a specified number of AutoFocus runs similar to Plate Solving number of failed attempts. I find that my focus generally improves if I run Auto Focus two or three times. As it is now, I have to be physically at the computer (or connected remotely) to trigger the “Run Again” button. A user set number of Auto Focus runs could assist in getting the best focus while the computer is unattended.

Cheers,

Gord

2

Just wondering if this might be possible?

3

Which SGP version are you using? This should not be the case with the quadratic fit algorithm (SGP beta version >= 3.1.0.295). With decent seeing conditions the reproducibility of AF results is excellent.

If you use one of the beta versions >= 3.1.0.295 and nevertheless are seeing an improvement when several AF runs are performed consecutively, I guess the cause is a bad centered first AF run AND a too large ‘step size’ setting. In this case try lowering the ‘step size’ somewhat.

According to my experience, with quadratic fit the HFRmax / HFRmin ratio should rather be in the range of 2 - 3 than in the range of 3 - 5 which was recommended previously.

Bernd

4

Generally when focus improves over multiple runs it almost always points to one of 2 things:

  • Backlash in the focus gears
  • Accuracy issues in the focuser (skipping steps, slipping, etc)

I would check the backlash or just add some backlash compensation and see if that resolves the issue. You should not need to run auto focus additional times as the motor should be fairly accurate (unlike telescopes, which is why the iterative slew is needed).

Thanks,
Jared

5

Thanks Bernd,

I’m using the current Beta version but I’ve noticed this in the past as well. I’ll try lowering the step size a bit and see if that makes a difference. The AF results are close 1.8x-2.0x usually which isn’t bad but not often repeatable. If I run say 3 times I get 3 close results which could be better or worse than the first run. Given the closeness of the results, I’m wondering if it might be due to seeing conditions. I hadn’t thought of that before, thanks!

Cheers,

Gord

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6

H Jared,

Thanks. As Bernd mentioned earlier, it could be due to step size or seeing conditions. I’ll try his suggestion and yours re backlash and see if that makes a difference. The AF results are always close but not often repeatable. I’m using a Starizona MicroTouch wireless focuser which has always been a good performer so I put the small variance down to either me needing to tweak my settings or seeing conditions.

Many thanks,

Gord

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