If you have shopped for telescopes recently, you may have come across various symbols, letter pairings, and codes that clearly mean something.
They often appear in the names and titles of telescopes along with numbers and other things that have some people scratching their heads. Each of these seemingly random pairings of words, numbers, and letters mean something and can tell you a great deal about the kind of telescope you are looking at without having to read deeply into the specifications.
One commonplace code is EQ which frequently appears in telescope names ranging from small budget scopes up to large expensive optical behemoths. As someone who has reviewed and profiled dozens of telescopes, I know exactly what these letters mean and a lot more.
EQ stands for equatorial and it tells us what kind of mount a particular telescope comes with. Many times, the name of a telescope will tell you the aperture size, the type of mount, and the type of telescope it is at a glance. For example, a telescope with a name like Celestron 130EQ Newtonian tells us that this is a 130mm Newtonian reflector mounted on an equatorial mount.
What EQ Mounts Are Good For…
Equatorial mounts are useful for things like astronomy and astrophotography because they take into account the rotation of the Earth during use. An equatorial mount aligns itself with the spin of the Earth so that it is parallel with the natural motion of the Earth. This allows you to keep a celestial object in view for much longer and easier than other kinds of mounts.
This is because, when compensating for the rotation of the Earth, you do not lose track of an object as quickly as other mounts. Instead of accounting for the motion of the Earth and the object in question, you only have to focus on the object’s motion. Remember, everything overhead is moving in some capacity, even if it does not seem that way.
Take Jupiter as an example. Without an equatorial mount keeping the Earth’s motion in mind, you would have to account for the spinning of the Earth which slowly moves which patches of sky are available to see at any given time, as well as the motion of Jupiter as it moves in its own rotation around the sun. By removing the motion of the Earth as a potential inhibiting movement, you are able to keep Jupiter in view with much less effort making the viewing experience more enjoyable.
Other Kinds of Mounts
While useful, equatorial mounts are just one kind of mount that is available for telescopes. Whenever you see EQ you know that it has an equatorial mount but there are other designations that tell you about different kinds of equipment that telescopes come with.
There is a variant of the equatorial mount called a German Equatorial Mount (GEM or GEQ) which is a popular version of the standard equatorial mount. The German style mount is able to easily align your telescope along the polar axis as well as the Earth’s rotational axis. Polar alignment allows for long term exposure of the night sky and has the sky spinning directly above your telescope instead of your scope following the motion of the Earth. This is used for those long timelapse videos and photos of the stars spinning overhead throughout the night.
AZ stands for altazimuth mount which is a common free moving mount. Compared to an equatorial mount that is designed to only be moved along one axis, an altazimuth mount moves along four. It is able to move up and down, side to side, with ease. This is a more freeing motion that allows telescope users to scan the sky more quickly but does not allow for easy motion tracking.
Learn The Code
Next time you are shopping for a new telescope or are doing research on new equipment, remember that those numbers and letters all mean something. Once you know what you’re looking for and looking at, the names will stop appearing strange and disjointed and will start reading like true words.
EQ stands for the equatorial mount. AZ for an altazimuth mount. The numbers are the size of the primary aperture. Together, these shorthand codes will save you time and energy allowing you to get a glimpse of the basic specs of almost any telescope at a mere glance.