Focuser questions - Temperature Compensation and Backlash

Hardware and software setups, autoguiding and plate solving parameters, etc..
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Posts: 128
Joined: Thu Aug 23, 2018 8:22 pm
Location: Missouri, USA

Mon Aug 19, 2019 8:19 am

I thought this might be a good forum topic for folks to reference back to one day. Now that my rig is running much better thanks to Hamza I am starting to go down some new "rabbit holes" to make my setup the best it can possibly be. One of those aspects is automatic focuser temperature compensation. My hardware for this is a Moonlight Focuser (2.5" style with the controller).

I can perform this either with the Moonlight driver or with Prism, I would assume that having Prism manage focus temp comp would be the better option, since Prism would be "aware" of the actual focuser position? -(according to what I've found if you enable TempComp in the driver, the driver will continue to report the same focuser position back to ASCOM/Software, but will be moving the focuser per it's temp comp settings. I'm not sure I like the idea of Prism "thinking" the focuser is at a certain position but in reality it's in another position).

*Assuming I want to use Prism for this, does someone have a workflow on setting this up?

Next with the focuser would be compensating for backlash in the focuser. Like any mechanical geared system there's always a certain degree of physical "slop" in the gears. The reference materials I've found basically say that you want to go with the direction of gravity (I think), meaning - Let's say hypothetically you're super human and can move your focuser manually to sub micron accuracy. In order to compensate for the slop in the gears you would find your focus point and then move the focuser ever so slightly to take up the slop in the gears so that the teeth are resting at the point where your image is perfectly in focus. - Bare with me if my understanding stinks!

*Assuming again that my above explanation is somewhat on the correct side, is there a workflow on measuring this and setting up Prism to compensate?
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