Greetings all. I've recently moved from using a modded DSLR on a star tracker to a full Narrowband rig and am still on the learning curve.
My optic is a William Optics refractor (with the 2-speed focuser) and a filter wheel and mono camera. I'm doing both Narrowband and LRGB. I use Astrophotography tool for running everything.
It's become clear to me my rig is missing a focuser and without one, it will not be able run unattended overnight and make filter changes.
So to my question. There's a few focusers out there (ZWO EAF, FocusCube, etc) that all seem to work pretty much the same way - ASCOM driver, electronic controller, stepper motor that drives the focus knob on the OTA.
My question is in regard to understanding how the focusing works. When I focus manually, after setting up the mount, I'll slew to a bright star, put on the Bahtinov mask, set the camera to Live View, and then adjust focus until the pattern is correct.
How does automated focusing work? I assume it does it without the operator needing to apply the bahtinov mask each time else it'd kinda be pointless.
Does it focus while on-target? Or do you have to designate a bright star for it to refocus on? How long does a focus run take (I kinda assume it has to image - adjust focus - re-image, rinse and repeat until focus is nailed)
I'm just totally in the dark as to how this actually works and I want to understand it before I spend money in case I ignorantly buy something that turns out to be unsuitable because of something I didn't know while I was shopping...
For reference - I'm looking at the "Pegasus Astro DMFC Premium v2" on Cyclops (don't know if I'm allowed to post vendor links on here so I'd rather not risk being booted, but it's easy enough to find).
Can anyone help me destroy another little bit of ignorance??