Let me give it another shot :-)
First, am sticking to current camera technology.
"Guiding" (to me), is making minor mount movements during a main exposure to ensure that the mount movement over the length of the exposure stays within (say) a pixel. Main objective -keep single subs sharp.
"Recentering" is after a frame has been taken - it plate solves the previous image and moves the mount so that the target goes back to the centre for the next image. Main objective - keep target incentre over a session so that you don't get huge black borders after stacking, recover from a wind gust, animal bump, or whatever.
With typical set of ZWO/QHY etc hobby astro cameras, guiding and imaging simultaneously with the same camera is not possible.
What you can do, in NINA, Sharpcap, Firecapture and others, is recentering with the same camera. You do need to set a tolerance for drift - after which recentering is triggered.
If the frame exposure is long, say 2 min like DSO, you can recenter with the same camera but the mount will get a correction signal only after 2 min. It has no way of correcting within those 2 min.
If the frame exposure is very short, like 10ms in planetary, Sharpcap or Firecapture will recenter much faster, in maybe a hundred or milliseconds (depending on tolerance set). Because of the very short times involved, this may be practically indistinguishable from guiding, but is technically recentering as the mount move happens only after the previous frame is analysed and not during an exposure.
Planetary capture has another feature called ROI centering. here the software moves the ROI to ensure the planet is centered in it even if it is moving all over the sensor. Again, it will look like the planet is steady in the centre, but this is a third animal, neither guiding nor recentering.
Hope that helps :-)
Novice here, however I'm hoping to do something along these lines as mentioned in the original post.
I have an idea and not sure if it will pan out but going to try it when my equipment arrives (AP 1100).
I've read some people saying that with a high end mount and good camera it may be possible to do unguided exposures for up to 2 minutes or longer. Is this correct?
I think this would work best if you can pre-build a model of the sky area you are intending to transit over so that any mount variations during the viewing session can be taken into account "in advance". Luckily there is exactly such a plugin for NINA called Astro Physics Tools (for AP mounts, see and https://www.youtube.com/watch?app=desktop&v=JMcEd1_FpjI ). By modeling the section of sky in advance and putting that model into the software it can predict the guiding needed and do it while doing exposures. Then you can also plate solve and recenter between exposures if needed.
Secondly, by using a good camera is it possible that you don't need 2 minute exposures? Can you get by with 30 sec or 1 min exposures? I'm not clear on this, however why can't you just combine 4 or 2 such images and get effectively the same as a single 2 minute exposure? There are probably some "reasons" I'm not aware of.
Currently I don't have a guide camera. I'm hoping to somehow get by without one, not because of the cost but because it seems wonky to me, especially if using a whole other scope which isn't inline with the optical train. I may add an OAG setup if I need to, but first I thought to try and figure out something more elegant.
Does anyone have advice on software that works better in combination with guiding software so that the problem of one program "grabbing control" of the camera is not an issue? For instance PHD2 is using the camera, then if I connect the camera in NINA it said connection to camera is lost in PHD2. I guess the expectation is you use a separate camera in PHD2, but is there some way around this using a pass-through plugin or something so both systems can see the same picture?