Recent trouble focusing SCT - lagging mirror?

@cmassa wrote:

I have a Rigel stepper motor on the stock focuser of my 8" EdgeHD SCT. With the new focusing system in SGP it has been working quite well but lately I'm not getting consistent focus. The right side of the V curve has much less slope which leads to SGP using the lowest focus point. I then get an out of tolerance warning on the focus.

Also, when watching the focus run there is a consistent shift of the stars towards the left and then a return as the mirror is moved to focus again.

This has been happening more and more lately. It is cooler out now and I'm wondering if this could be due to the mirror lagging behind? I couldn't find one but is there a setting to put a delay between focus exposures? If not, what would you think of this as a feature request?

Is my reasoning correct or is there some other problem I need to correct or look for? If the mirror is lagging significantly, does that mean the scope should go back to Celestron for service? I think it's 4 years old now.

Yes, the mirror locks are loosened -- I checked that first.

Here's the focus pack for that graph:
Autofocus pack

Thanks for any advice,
Chris

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