Have you ever felt lost when looking for a telescope? Especially when you come across descriptions of different telescope mounts. Wouldn’t it be great to have telescope mounts explained in a simple format…
I remember when I first started looking for a telescope, I was bamboozled by the different types of mounts available. But after doing some research and trialing a few of the types, I got to know what they were about. In the following, you’ll find the different telescope mounts explained with diagrams and how-tos.
The alt-azimuth is the telescope mount for beginners. For astrophotography, choose more advanced mounts like the equatorial or Go-To mounts. Dobsonian mounts are simple, stable, and affordable, but are bulky and also unsuitable for astrophotography.
Who is this for? Anyone looking to buy a telescope or has already bought one and wants to get the best from it by knowing how to use a telescope properly starting with understanding how the mount performs.
Why is this important to know? Understanding how the different telescope mounts perform will help you in choosing the best one for you if you’re in the market for a new telescope or mount. In using your telescope, by knowing more about the mount, you’ll get a better experience. You’ll know what to expect. It will also reduce the likelihood of damaging your equipment through improper use.
What is a telescope mount?
A telescope mount supports the telescope. It has moving parts so that you can point the telescope at the stars or other objects and adjust it as these objects move. It also allows you to free your hands for focusing, swapping eyepieces, taking notes, checking star charts, and other activities.
When talking about telescope support, we generally think of the mount and tripod combined. But, not all mounts include a tripod, e.g., the Dobsonian. Compared to the Dobsonian, in most reflectors and refractors, the mount requires a stable tripod to keep the telescope steady.
Best telescope mounts for your purpose
Telescope mounts’ design and workings can differ.
- Best telescope mounts for astrophotography: Equatorial and computerized Gotos
- Best beginner or easiest telescope mounts to use: Alt-azimuths
- Best simple and stable mounts: Box-rocker types like the alt-azimuth mount of Dobsonians
Alt-azimuth mounts explained
The alt-azimuth mount type allows you to move the telescope up and down and left and right to point the telescope at any object in the night sky. With this design, you have two axes of rotation: up and down (horizontal) for the altitude and left and right (vertical) for the azimuth.
The altitude AKA elevation is the verticle angle in degrees of an observed object from the horizon, which is 0º on this axis. The azimuth is the horizontal angle in degrees, which rotates from north (0º), to east (90º), south (180º), west (270º), and then north again.
To use an alt-azimuth mount to look at the Moon for example, you would adjust the altitude axis to tilt the telescope up and down and the azimuth axis to move the telescope left and right until the Moon is in view.
Another example: To see Venus through a telescope, with its position at altitude of 45° and azimuth of 90°, you’d rotate your view to the east, which is 90° on the horizontal axis, and then elevate it to the 45° point, which is halfway between the horizon and zenith, which is directly overhead — altitude of 90º.
Alt-azimuth mounts are simple to use and generally cheaper than the equatorial types. This is the advantage of these types, which you’ll find in kids’ telescopes and beginner telescopes that are economical buys.
If you intend on doing astrophotography, steer away from an alt-azimuth mount. A manual alt-azimuth mount requires different rates of rotation of both axes. With these types of mounts, it’s not easy to keep up with celestial objects as they appear to move across the sky with Earth’s rotation.
Dobsonian mounts explained
A Dobsonian telescope mount is a type of alt-azimuth mount that is designed to be simple and affordable. It was invented by John Dobson in the 1960s as a way to make large telescopes more accessible to amateur astronomers.
The Dobsonian mount is characterized by its box-like design, which consists of two parts: a wooden or metal base that sits on the ground, and a cradle that holds the telescope tube. My article on the pros and cons of Dobsonians covers more about these types of telescopes.
It sits on the ground and has two axes of rotation: the azimuth axis, which allows the telescope to rotate horizontally, and the altitude axis, which allows the telescope to rotate vertically. The cradle that holds the telescope tube is attached to the altitude axis and can be moved up and down to adjust the height of the telescope.
The downside is that it is not well-suited for astrophotography, as it does not track the motion of the stars in the sky. Another is that it can be difficult to use for objects near the zenith, as the altitude axis can be hard to reach.
equatorial telescope mounts explained
An equatorial telescope mount is designed to move in a way that mimics the rotation of the Earth, allowing you to keep your telescope pointed at the same object in space for an extended period.
German equatorial mount or GEM is the most popular equatorial mount used in telescopes. What to know:
- Declination (Dec): The declination plane is the latitude in the celestial sphere (above us in the sky vs. on Earth). It’s measured in degrees with 0° DEC at the sky equator and + values going north to the max of +90° at the north pole, while -values run south to the max of -90° at the south pole. This simulates the lines of latitude in the global positioning system used for land coordinates.
- Right ascension (RA): The right ascension plane is the longitude in the celestial sphere measured in hr min sec.
An equatorial telescope mount can accurately track objects in the night sky.
Equatorial mount vs altazimuth
The use of right ascension (RA) and declination (DEC), coordinates of the International Celestial Reference System (ICRS), distinguish the equatorial type of telescope mount from the altazimuth.
The right ascension axis is aligned with the celestial pole. This is the point in the sky that intersects with the Earth’s axis of rotation. In the Northern Hemisphere, the celestial pole is located near the star Polaris, while in the Southern Hemisphere, it is not marked by a bright star but other means are used as describe further down.
Equatorial (EQ) mounts are more mechanically complex than the alt-azimuth types. They can be more difficult to set up and use than other types of telescope mounts, and it may require more skill and practice to track objects accurately. The beauty of an equatorial mount is that by rotating a single axis at a constant rate, you can follow the celestial object as it appears to move with the rotation of the Earth.
Equatorial fork mount
The forked equatorial mount involves a two-pronged fork sitting on a wedge. The wedge or base is aligned with the Earth’s pole and is one axis of rotation and the prongs are the other.
This type of mount is seen in the short-tubed Schmidt-Cassegrain telescopes (SCTs).
German equatorial mount explained
The best way to describe a German equatorial mount (GEM) is to think of the letter “T”, where the stem of the “T” is the axis that is aligned with the Earth’s pole and the top of the T is the declination axis.
Mounting a telescope
Large equatorial mounts can be heavy. You will have to disassemble the mounting for transportation and reassemble it at the location where you intend to observe the night sky.
Once you have the tripod set up evenly, add the mount to the top of the tripod by placing the protruding base of the mount into the indentation at the top of the tripod. Usually, there is a knob under the tripod head to secure the mount in place. Tip: Take care not to overtighten.
Put the latitude adjustment screw in place by threading it into the hole at the back of the mount close to the tripod head. Screw it in enough to hold it in place only as you will need to adjust this when setting the local latitude.
Why you need an equatorial mount for astrophotography
Equatorial (EQ) mounts are better at tracking a sky object you want to shoot. Although it doesn’t seem like it, the Earth is rotating. At the same time as you are trying to capture good astro-images, you are moving relative to that point in the sky. The rate of movement is roughly 1,000 miles per hour (at the equator), according to an article in Scientific America.
Because the celestial body is so far away this movement is not obvious to you. However, it can affect your shots. You may see motion blurs or trails.
With an alt-azimuth, to track an object, you need to move the scope both horizontally and vertically and you’ll find the eyepiece field of view will rotate. This is not ideal for astrophotography.
With an equatorial mount, you only need adjustment on one axis, the right ascension (RA) axis, once you’ve locked onto an object to follow it. In a manual mount, this requires turning the RA control only.
A computerized EQ mount offering precise tracking, paired with a tripod that’s robust enough to hold the weight of your telescope steady, is ideal for high-accuracy capture of detailed images of the night sky. Orion telescopes offer a range of computerized EQ telescope mounts (GoTos) like the following favorite…
If you’re looking for a heavy duty GoTo mount for all your observing or astrophotograph… [More]
How do you use an equatorial telescope mount?
For the EQ mount to track celestial bodies across the sky it needs to be polar aligned. This means that the RA axis runs parallel to the Earth’s axis of rotation. You need to do this not only for tracking objects across the sky (at high magnifications, especially) but also if you intend to do astrophotography.
There are slow-motion control knobs for axes of RA and Dec. To move the telescope some distance across the sky, it is best to loosen the RA and Dec clutch knobs on the side of the mount and move the scope by hand. Once you have it in the desired position, tighten the clutch knobs again.
How to polar align an equatorial mount
It amounts to setting the latitude on the mount to your current latitude (where you are using your telescope) and then rotating the mount on its azimuth axis so that it points true north (vs magnetic north). If you are in the northern hemisphere, find the star Polaris and line up the RA axis with it. It needs to be more accurate if you intend to do astrophotography.
This video explains how to polar align a German equatorial mount in the northern hemisphere with the help of the Polar Finder app …
How to polar align an equatorial mount in the southern hemisphere
In the southern hemisphere, in places such as Australia that offer some magnificent stargazing locations, you need to point true south.
Here, you need to align the RA axis to the southern celestial pole (SCP). This is slightly more challenging in the southern hemisphere because there is no single bright star such as Polaris that is associated with the southern celestial pole.
The few ways used by amateur astronomers in the southern hemisphere to align the RA axis include laser alignment, known star alignment, drift alignment, and the Crux.
This means you use a laser to align your scope. Regarding laser alignment, local regulations can apply to the use of lasers and, in many cases, they may be banned or you need to register their use.
Known star alignment
The known star approach is for computerized mounts AKA GoTos.
The drift alignment starts by focusing on a bright star that is low on the horizon. If the star drifts north, your RA axis is too low, if it drifts south, it’s too high. The next step is to focus on a bright star on the Meridian (right about your head). If that star drifts north, then rotate your mount clockwise (west) to adjust. If it drifts south then rotate your mount anticlockwise (east) to adjust. Repeat the steps until you get it accurate.
Using the Southern Cross (Crux) and pointer stars
With the latitude locked into the local latitude and the telescope set towards the south celestial pole (SCP) on the azimuth axis, the Dec axis is set to 90º and clasped in place. The telescope needs to be sitting strictly over the tripod. To achieve this, it is moved on the RA axis until in position and then clasped in place. It is now in the general direction of the SCP.
Depending on the time of year and the night, the Southern Cross (AKA Crux) is a well-known marker and southern hemisphere constellation to determine the south. Draw a horizontal line between the bright star adjacent to it, Hadar, and Achernar to the west. At the center of this line, where the Crux points to, is roughly the SCP.
Use the finder scope to point the telescope to this area (without moving the Dec axis). Once aligned with the SCP, tighten the azimuth and latitude axes and continue using the telescope based on the celestial coordinate system, east-west (RA) and north-south (Dec).
These notes are taken from this video, which gives great visual coverage of how to polar align an equatorial mount in the southern hemisphere using the Crux.
GoTo mount explained
A GoTo mount is computerized. It will automatically go to a selected object you wish to observe or track. These mounts are more expensive than the manual types and are covered in detail elsewhere. You can find more about these in my guide to the best telescopes for planet viewing.