Here is an example of what you can get with a single frame exposure these days. This is Comet C/2011 L4 PanSTARRS which is now almost twice as far away from planet Earth as Earth is from the sun. K5 IIs, O-GPS1, 45 seconds, Takumar 135/2.8 @ f/4, ISO200, EV +3.8, made into a monochrome for better contrast, a touch of raw denoise and a lot of tone curve manipulation. When the comet was at its closest approach this past spring, we saw it in profile. The Earth has now passed through its orbital plane and we are starting to see it from the other side, "looking back" at it. The comet's apparent motion is to the left of the frame opposite that of its long "anti-tail" which points to the sun. There is no doubt that stacking improves the signal to noise ratio. But this is still a useable frame.
Jack