Astrophotography isn't limited to cameras attached to telescopes, it also includes shots taken with standard camera lenses "piggybacked" on a scope or somewhere else on the mount. My piggyback rig varies, but I almost always have something set up, even if it's just to get a wider field view of the area around my main target. Standard lenses are handy for shots that require much wider angles of view than can be had with telescopes - shooting the vast expanse of the Milky Way, for instance. In addition, they're much more portable than a telescope, so you can travel with them more easily.
On the K-1000, I only use the 35-70mm zoom that came with it, and that's fine for star trails. For wide-field guided shots of deep sky objects, zooms are usually a bad choice, since they often slip during the exposure (especially the push-pull kind), and typically have compromised optical designs to accommodate multiple focal lengths. Auto-focus lenses can also slip focus during an exposure, since their focus rings are typically loose, in order to be easily driven by the camera's auto-focus sensor/motor. For this reason, I prefer fixed (prime) focal length lenses with manual focusing. After several years of building my collection of Nikkor lenses, I now have the following:
20mm f/2.8 AF-D Nikkor
24mm f/2.8 AIS Nikkor
50mm f/1.2 AIS Nikkor
85mm f/1.4 AIS Nikkor
135mm f/2 AIS Nikkor
180mm f/2.8 EDIF AF-D Nikkor
300mm f/2.8 EDIF AIS Nikkor
This is pretty complete set for my needs, but I'd like to add 28mm, 35mm, and 105mm lenses to round out the collection.
After getting into medium format work and acquiring two Pentax 6x7 cameras, I subsequently settled on two lenses:
105mm f/2.4 Pentax 67
200mm f/4 Pentax 67
These two lenses cover most anything I'd want to shoot, and wider fields can be had with my Fuji rangefinder cameras (at 65mm and 90mm on 6x9 format), but there are a few targets that would benefit from the slightly larger FOV of the well-regarded 165mm f/2.8 Pentax 67 lens, so I might pick one of these up some day. The 200mm is razor sharp - one the best lenses I've ever used.