I would have to disagree about noise being a problem with Canon it will be more obvious on a non DLSR  Richard is quite correct about the menu and the options to improve the long exposures

The option suggested is very useful when taking long exposure shots (in bulb mode). One of the big problems with long exposure shots at night is that you sometimes get “hot pixels” – these show up as coloured specks and are particularly noticeable against the black sky in nighttime shots. By switching this function on (to 1, rather than 0) , the camera takes two images, one with the shutter open and one with the shutter closed. It uses the second image (with the shutter closed, which takes the same amount of time as the exposure of the first image) to deal with the hot pixels in the first image, by subtracting the noise from the second image from the first. This is very useful, and it’s incredibly effective – although it does mean that you have to wait twice as long for your shot. Remember to switch it off when you don’t need it. It’s worth noting that the noise reduction will only kick in on exposures of 30 seconds or more

However, hidden in those menus are some other features that can be very useful in certain circumstances – the most useful of these apart from  the long exposure noise reduction,  are shutter-curtain sync and mirror lockup. Try them lockup will for example allow the main cause of unsharp images the vibration caused by the mirror locking up you set that option press the shutter once and then again to expose the shot..

Danny O'Byrne  http://www.digitalartzone.co.uk/

"All the technique in the world doesn't compensate for the inability to notice" Eliott Erwitt