Camera and Lens for Photography of Faint Meteors

The camera body has no great influence, since it is just the film holder. Of course, the camera must allow time exposures and the easier it is to handle in the dark the better it is suited for astronomical purposes. In particular, problems may occur with cameras driven by electronics. If it is not possible to switch off the automatic controls it may not be possible to make long exposures or the batteries may wear off very quickly. Also cold winter nights are likely to lower the performance of the batteries. Long exposures are possible only if the camera shutter has either a 'B' or a 'T' position. ('B' implies that the shutter is open as long as you push the release button. 'T' opens the shutter once you push the release button, and it remains open until you push it again.) If you use 'B' on your camera, you will need a lockable cable release, while 'T' allows exposures without such a device. Sometimes a cable release may cause troubles. Some cable releases are badly affected by humidity or cold, and should be tested before each use.

The lens is of essential influence for the result. It must allow a good definition and should be sufficiently fast. Very good results can be obtained with the f/1.8, f=50 mm standard lens of small cameras. Unless very short exposure times are applied, it is not useful to use a faster lens. Longer focal lengths more often result in truncated meteor trails, unless the cameras is pointed close to the radiant of the active shower. Shorter focal lenghts often result in disappointing photographs, not in more meteors.

Of course, when you have another type of lens available you can use it without problems. Within a certain range of focal lengths (15mm...80mm) we may compare the effectiveness of different lenses using the simplified measure E, defined as: E = d2 / f, where d is the linear aperture of the lens, and f is the focal length,both in mm. If you prefer to use the aperture number r, you may write: E = f / r2.

Some construction work is required when you want to heat the lens of your camera. Unless you operate in a very windy or arid area, dew will form on the lens of your camera during the night when it cools down. You can heat your lens (or the air in front of your lens) with one or more electrical resistors, connected to your car battery (assuming you drive out of the city to a dark spot). A possible construction is drawn to the right, using a small piece of 2 inch plastic pipe that fits around the lens.