Just remember that when you do longer exposures from a tripod with a cable release, there are a few important things to watch (depending on your camera and functions).
1. Your camera should have a "Mirror lockup" mode (MLU). This flips the mirror up well before the shutter opens, so that the act of the mirror moving will not cause shake on your shot.
2. Your camera may well have a long exposure noise-reduction mode. I would suggest using it for exposures over 5 seconds.
3. If you are using a camera with image stability (either in body or in lenses) its a good idea to turn it off before shooting long exposures from a tripod. Some cameras are able to sense that the camera is tripod mounted, and switch of IS automatically, but not all.
4. You WILL see hot pixels in your image when doing longer exposures. Long exposure noise reduction can help mitigate this, but it never normally removes it totally.