I have an *istDS and have been really enjoying taking pictures of the night sky. I have an f/1.7 lens that came with one of my Ricoh cameras. I set the camera at 800 or 1600 ISO and set the shutter for 8 or 10 seconds to get pinpoint pictures of constellations even at f/1.7, showing stars as dim as the eye can see. I use the 2 second self-timer to eliminate vibration. Then all I do is mount the camera on a tripod and point it at different things and snap away. I just love the fact that all my good old Pentax and Ricoh lenses get to be used after being neglected for like ten years or so. I have a 2.8 135mm lens that I still plan to use and an old and very heavy 28-200 zoom which I may replace with something much lighter and more convenient.
The viewfinder is so good that I can get a very precise focus on closeup objects with the 1.7 lens.
It would be nice if the camera had image stabilization. Or should I say individual lenses? I also would like it if it had a full frame imager so I could take full advantage of available wide angle lenses. I suspect that in the future Pentax will come out with something like that. Canon is coming out with one but it will cost over US$3000