Have been messing around with it and get wildly varied results and it seems no matter the ISO, noise is a problem. I've tried the kit lens as well as a couple fast wide angles. Has anyone found a sweet spot in regards to shooting starry skies?
I've since found the "long shutter NR" needs to be turned on to drastically reduce noise in long exposures. Some modes turn it on for you some don't. Best just to keep it in manual exposure mode.
Mojo, Also you can change the ISO step to smaller increments Kholi has said 320 is the sweet spot in the lower range, maybe there is an intermediate setting in the higher iso range that is good too.
You can change to smaller increments in the setup menu.