You could buy an iOptron or similar star tracker. I have a Fornax one. A week ago: 10s at ISO1600 and f4.4 with the zoom at 128mm (cropped below a little). You just screw it onto a regular tripod, plug the thing into a 12V source, point it vaguely at the north star and the star trails disappear. Go to r/astrophotography on Reddit and all the comet pics will have the name of the tracker they used and the camera settings. Unless they have a Sony A7R and can shoot at ISO 1billion.
