Choosing the best lenses for nightscapes
AFTER A SOLID TRIPOD, a good-quality, fast lens is the best investment an aspiring astrophotographer can make. It need not be an expensive purchase. But it does require research, as the lens market has become rather complex in the past few years, to say the least.
With a focus on choosing wide-angle lenses for nightscapes, here’s my guide to buying the best lens, whether it be for your old faithful digital single lens reflex (DSLR) or for one of the newer digital single lens mirrorless (DSLM) cameras.
Aperture is key
While daylight photography is bright and forgiving, at night we need speed. The photographically faster the better. This ‘speed’ refers to the focal ratio, or ‘f-ratio’ of the lens, which is its focal length divided by the maximum diameter of the internal iris of the lens (not to be confused with the size of its front element).
Twilight scenes, conjunctions, eclipses, noctilucent clouds, star trails, and even bright, moonlit nightscapes are captured well with f/4 to f/5.6 lenses. However, the subjects many astrophotographers want to capture — the Milky Way, meteor showers and aurorae — demand a lens with a maximum aperture of f/2.8
