Night photography panorama technique
This night panorama is composed of 10 vertical images shot with a 28mm lens at f/8 on a Canon 5D Mark II. I use an L-bracket on the camera for verticals, and an Acratech Leveling Base on my tripod to keep the plane of rotation level. The leveling base saves time in the field, and ensures you don't lose too many pixels at the edges of your shot when stitching. The camera can be tilted slightly upward to change the sky/ground relationship, and the pano will still stitch fine. I don't use a nodal slide. The pano was stitched using Photomerge in Photoshop CS5 using the cylindrical setting. Keeping the exposures short is necessary when there is cloud movement in your pano. Shorter exposures also help the stars look correct by minimizing star trails.
The best ISO for night photography
For digital night photography, shooting at the native ISO of the camera yields the least noise. Typically this means ISO 100 or ISO 200, but it's best to do some controlled testing with your camera to see what works best. I often shoot at ISO 200 with the 5D Mark II and find little difference in noise between ISO 100 and ISO 200. A properly exposed shot at ISO 200 is going to have a better noise profile than an underexposed shot at ISO 100.
Due to the speed of the clouds I bumped the ISO to 800 to keep the exposure time down to 45 seconds for each shot. Sometimes the rules about the best ISO for night photography need to be broken in order to get the shot. This is especially true when shooting clouds. The weather was around 40 degrees, which helps quite a bit with keeping long exposure noise at reasonable levels. Only a minimal amount of noise reduction in Lightroom was necessary. Make sure to test your camera's capabilities before an important shoot, and review the images to decide how much noise you can tolerate. Pay close attention to the the temperature when testing -- the colder it is, the more you can push the limits of short exposures with high ISOs, and long exposures without noise reduction.