Originally posted by downhill Dr. Who I have no idea. It was something I read on a forum about astrophtography. Another had asked about using a Dobson with GoTo features and one of the answers was that the back plane issues needed to be solved. It's why I was asking here because I'm not a member there.
After more reading though, it seems I've found my answer.
What you should realize is that a Dobsonian mount moves in small steps in the horizontal (Azimuth) and vertical (Altitude) directions. Thus, with a Dobsonian Go-To telescope you may keep the cenral object centered in you field of view but, as Dr-who says, stars away from the centre will NOT keep their position during longer exposures. They will rotate in small arcs that become longer the further away they are from the centre. That is what is called Field Rotation and you will need special software (not just ordinary stacking software) to do a digital de-rotation of your field in post-processing. Or, you will need some means to rotate your camera/sensor to counter the Field Rotation.
What you see in this thread, when we talk about images taken with telescopes, is mostly from telescopes (Refractors, Newtonians, Catadioptrics) mounted on an Equatorial Mount. Here, you have one axis of rotation parallell with the rotational axis of Earth, i.e.: pointing towards true georaphical North or South, and with such a set-up you avoid the problems with Field Rotation. If the axix is properly aligned all stars will keep their places during exposure.