Contributed by: David Wilkins
There are some things that are absolutely essential for making a star trail shot. You must have a tripod to hold your camera steady during the shot. You must have a method of holding the shutter open for longer than 30 seconds. Your battery must be able to keep the camera going for at least one hour, preferably 2 hours.
A good star trail shot needs a one-hour or longer exposure to make a good trail. That means the camera can’t move during this time. Your tripod must be sturdy and in a stable position. An external weight, such as a bag of rocks, can be hung on tripod to give it more stability. The exposure mode must be set to manual and the shutter speed to bulb. In the bulb setting the shutter stays open as long as the button is pressed. The shutter can be kept open with a cable release that can be locked with the button depressed or a cable release with an interval timer can be used. Nikons that used the infrared remote will time out after 30 minutes. For an exposure longer than 30 minutes you must use a cable release. If your battery dies during the shot, you will get nothing. You must be confident your battery can make it during the entire exposure. Testing is one way to gain that confidence. Set the camera up as if you are doing a star trail shot, but leave the lens cap on. Do a one-hour exposure and see if the battery lasts and then do a two-hour exposure. Past experience says that no-name batteries will not make it. Mark your batteries that are capable of 1-hour continuous use and put a fully charged, good battery in the camera just before the shot starts.