any chance for nice star shots with a nikon D80? at ISO 400-500 I feel already close to the max regarding noise.
I got some wide open Lenses though from 11-16mm 2.8 50mm 1.4 and 17-50 + 80- 200 mm 2.8

Good luck getting decent star exposures using these iso's. Incidentally I have found from practice and at the advice of others shooting high iso it's best to over expose perhaps 1/3 of a stop to control noise. This is true for Nikon and Canon and my be true in general for all digital cameras. You also might want to consider using the "optimized" iso's for your camera. Some iso's are derived from software and may be noisier than the lower iso preceding it. From what I understand the best iso's for my Canon cameras are 160, 320, 640, 1250 2500, 5000. Not sure about Nikons. So there are refinement you can make.

Best thing is to practice and see for yourself.

Good Luck.

Brian

Hi,

For limited in exposure time by the movement of the earth. A working rule of thumb is

600/fl = max exposure time in seconds...

fl= focale lens