Bulb settings Can anyone help

[newtodigital1954]

I am using a
Canon EOS Rebel XS
Bulb setting 90sec
Apeture 4.5
ISO 1600
Noise Reduction used
Lens Stabalizer on
How can I get photos like this less grainny?
I can use all the help I can get on time lapse/night photography.
Sample photo : http://www.flickr.com/photos/rainbowblues/

[Nighthound]

1600 is a bit high for the Rebel XS unless outside temps are cold. Electronic/thermal noise caused by repeated exposures, LCD previewing is an obstacle in itself so I'd suggest staying at ISO 800 in milder temps.

If you stack multiple exposures via software like Deep Sky Stacker you can subtract dark frames from the stack to remove noise pattern. Dark frames are taken with the lens cap on (at the end of a shooting session would be fine) to record the same noise level/pattern that you good data will contain.

I don't use in-camera noise reduction or any in-camera settings that can be better handled in post process. No need for stabilization in tripod long exposure work, just be sure your tripod is sturdy. Use mirror lock if you have it and a remote switch to trigger and end exposures.

EDIT: Forgot to mention, always shoot RAW.

[pickupman92]

If you go on anything over about 15 seconds you're going to get star trails... because the earth is moving. I noticed that in your sample image.

I'd suggest trying different Fstops, from 3.5-8.0 all using ISO 400. You may also want to use a 2 second timer if you don't have a switch to start. Like Nighhound said, go ahead and turn off image stabilization.