Last weekend I had the chance to make my first attempt at photographing star trails. The idea of this type of shot is to point your camera at a fixed location in the night and make an exposure long enough so that the stars will appear to move across the sky as the Earth rotates. Making star trails can be fun and gratifying but it requires a certain amount of commitment on the part of the photographer. For best results, you need a dark, clear sky, devoid of light pollution. This means you'll likely have to travel far from your home and you may have to get up late at night after the moon has set. Making the exposures also requires a fair amount of time. A single image can require a cumulative exposure time of an hour or more. For these reasons, it's helpful to know what your shots are likely to look before you invest time and energy making start trails. This is not a situation where "chimping" and correcting is practical. In this blog post, I provide some help for pre-visualizing star trails. I hope this information will help you make the star trail shots you expect, with a minimum costly trial and error.
