This telescope glossary is designed to help you understand any acronyms or terms you may not be familiar with when reading our articles. It is arranged in alphabetical order.
Alt-azimuth mount (Altaz, alt-az)
Altitude and Azimuth are the 2 directions that correspond to up- down and left – right in telescope mounts. Thus, an altaz is simply a mount that you can pan upwards and downwards and swivel side to side. Altaz mounts are great for beginners due to their simplicity and low cost, and are just fine for visual astronomy and short-exposure astrophotography. However, for long-exposure deep-sky astrophotography you need an equatorial mounting.
The diameter of the main (objective) lens or mirror of the telescope, usually ...