A few months back I was searching for info for doing autoguiding on my 6SE and frankly I couldn't find any info that really matched my needs (or thoughts). Most of the info was from an AP POV for long exposure tracking, that the SEs simply can't do in alt/az, or a few successful but mostly unsuccessful attempts with a wedge and RA autoguiding,. But I really couldn't find much of anything if just wanting to keep the object being imaged "near" the center of the imagers FOV from occasional nudges in alt/az mode and taking many short exposure (< 30 sec) frames (lucky imaging). Similar to what I guess Firecapture can do on planets?
Maybe this is in part an autoguiding software issue too as I think about it, but my initial thoughts are to nudge the object back to center every few secs up to once a minute or so to keep it better centered for live stacking or the acquisition of FITS, SER, or AVI files. Sure you'd lose a few frames due to scope travel during the "nudge" but big deal if enough good frames are captured. Best case would be if the autoguiding software and acquisition software could be synced such that for the "longer" short exposures (say the 1 to 30 secs ones) the object is "nudged" back near center with say a 1 sec mount settle time before each exposure. Field rotation is still an issue but just having the object or region of interest kept close to the center of the FOV during the whole acquisition would be a big plus. Enough times I've had the object slowly drift out of the FOV of my 6SE while livestacking and then need to recenter, wait for the mount to start tracking again as best it can, and then restart the image acquistions. Some days (er nights??) the tracking is pretty darn good but others not so much so having the ability to have the object automatically recentered would be fantastic!
I figure (with little real autoguiding knowledge here) even with unsynced nudges and exposures that doing a recentering every ~60 secs with 5 sec or less exposures should give a lot of useable frames for the non-live stacking type acquisitions for post processing and when live stacking the frames with mount movement would just immediately get thrown out.
Somewhat more specifically to the SE mounts, gear backlash is an issue, but I would think setting the backlash settings so there is a small jump in the image upon direction of travel reversal would pretty much guarantee every time the autoguiding software says to move in a certain direction all the backlash would be taken up and the image at worst would at least move some small distance back towards the desired center location albeit with a small jump. (EDIT: Maybe backlash wouldn't be that much of an issue here after all. Even if the backlash wasn't taken up every time the software sends move commands it would eventually be taken care off once the objects drifts too far of the center and then a larger magnitude move command would be issued getting the object at least close to center again.)
I don't understand why a cheap, could be ~$150??, Svbony SV106 (60 mm, F/4, 240mm FL) guide scope with centering rings and dovetail (~$83) and there SV105 2Mp 1/3" CMOS imager (~$60) couldn't be the starting point for an autoguiding setup. The Svbony states the AV105 imagers works best with 400mm to 800 mm FL scopes so maybe throw in a cheap 2x Barlow to get the scope to 480mm FL and F/8. Right now I don't know what the FOV at the native F/4 is, and of course at F/8, so there may not be enough stars to guide on with this particular setup. And that 400mm to 800 mm optimum for the SV105 is for obtaining the best image quality and that shouldn't really be necessary for guiding unless the stars are so poorly focused that the now diffused signal doesn't allow for guiding. Another more expensive option at about $350 would simply to use the Orion Magnificent Mini Autoguider for a one stop shop solution.
Now continuing to show my ignorance and thoughts on autoguiding on an SE. Could something like SharpCap, which I mostly use for my image acquisitions, autoguide by using a bright star near the center of an object being imaged and nudge the scope based on that? For example, many galaxies have a very bright central core. Why couldn't SharpCap, or other acquisition software, sync on that bright core and occasional push that core back to the center while livestacking?
I really appreciate any inputs or thoughts as to how to keep the object being viewed with the 6SE, 8SE or similar alt/az scopes near the center while doing lucky imaging or while livestacking.
Edited by rnyboy, 16 September 2020 - 01:35 PM.