As per Robin Glover's (SharpCap) videos, another game-changer has been the advent of modern CMOS sensors. I think that his point is that their lower read noise means that many shorter exposure images can be stacked to be equivalent of longer exposure CCD images or single film exposure.
Not having to accumulate photons in a single exposure (film) or a fewer, longer exposures (CCD) reduces the precision of tracking required to the point where even the use of an Alt/Az mount is feasible for DSO imaging, if you are not chasing ultimate perfection that is.
I may get flamed for venturing this opinion but I think that it has opened up DSO imaging to many more AP enthusiasts.
There is no doubt that PC software such as SharpCap, FireCapture, DSS, PixInsight, et al are also instrumental. They make image capture and post processing more productive and easier to accomplish.
Edited by Rac19, 16 April 2021 - 06:25 PM.