Computerized Telescope Knowledge Center
Computerized Alt-Azimuth Mounts
An “alt-azimuth” mount is one of the most simple types of telescope mounts on the market. Simply put, an alt-azimuth mount moves up-down (also known as “altitude”), and left-right (also known as “azimuth”). Computerized alt-azimuth mounts are very simple to set up and will already know the azimuth and altitude of any objects in the sky based on your GPS coordinates and date/time.
Most alt-azimuth computerized mounts simply require you to input your GPS coordinates, the date, the time of day, and then a basic alignment on some bright stars in the sky. Some popular computerized alt-azimuth mounts might include the Celestron NexStar series of telescope mounts, as well as the Sky-Watcher Virtuoso series.
Advantages of a Computerized Alt-Azimuth Mount:
- Can be set up and ready to go in a few minutes
- Very portable
- Usable for short-exposure astrophotography (planetary/lunar)
Disadvantages of a Computerized Alt-Azimuth Mount:
- Not usable for long exposures due to field-of-view astrophotography
- Usually limited in payload capacity
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Computerized Equatorial Mounts
An “equatorial” mount is similar to an alt-azimuth mount. However, the key difference here is that equatorial mounts move based on an entirely different set of coordinates: Right Ascension and Declination. You can think of Right Ascension as your stellar “longitude” in the sky, and your Declination as the stellar “latitude”. Equatorial mounts are essentially alt-azimuth mounts but tilted at an angle based on your GPS longitude. This also corresponds to the altitude at which the north star (Polaris) sits in your sky. This allows the equatorial mount to follow the movement of celestial bodies on a single axis as they rotate around Polaris throughout the night. This design eliminates field-of-view rotation and makes them ideal for astrophotography.
Polar alignment and balance in both the right ascension and declination axis are necessary steps to perform to get the best out of an equatorial mount. Precise polar alignment and balance are a prerequisite for pinpoint stars and sharp detail. While precise polar alignment is not critical for visual astronomy, failure to properly polar align or balance your mount will result in star trails should you attempt astrophotography. The longer the exposure, the stronger your signal-to-noise ratio will be, thus weighing the importance of proper polar alignment! Due to the niche design of equatorial mounts, they’re often sold as standalone units. Good examples of equatorial mounts include the Sky-Watcher EQ6-R Pro, Celestron AVX, and Celestron CGX.
Advantages of a Computerized Equatorial Mount:
- Eliminates Field of View Rotation due to alignment with Polaris
- Better tracking and Go-To accuracy
- Can be used with a wide variety of telescopes
- Generally have a heavier weight capacity
Disadvantages of a Computerized Equatorial Mount:
- More expensive than an equatorial mount
- Significantly heavier, especially with counterweights
- Can be cumbersome for visual astronomy as a result of the tilt of the mount head
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Portable Startrackers
Recently, there has been a trend toward “travel-sized” equatorial and alt-azimuth mounts. These mounts can fit into a camping bag or a checked bag on an airline flight. This is a great option for those interested in portable visual astronomy and astrophotography. However, these star trackers are generally significantly more limited in their capability.
A popular new product from Sky-Watcher is their new Sky-Watcher GTi mount. With a weight of only 5.7 lbs, the GTi is presently one of the only portable star trackers that are equatorial mounts with tracking and Go-To on both right ascension and declination. As a result, the GTi is a fantastic option for astrophotography on the go. The GTi can also connect to a computer with programs like NINA, Sharpcap, et cetera. The Sky-Watcher Star Adventurer 2i and iOptron SkyGuider Pro are two additional options one may wish to consider. However, these two only track on a single axis (right ascension). As a result, you’ll have to manually adjust the declination to frame up your target.
Advantages of Portable Star Trackers:
- Can easily be fit in a camping bag and checked bag
- Come with many of the same features larger mounts have
- Can fit DSLRs and small telescopes without heavy counterweights
Disadvantages of Portable Star Trackers:
- Limited weight capacity
- Often only track on a single axis if in equatorial mode
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Computerized Mount Facts: Choosing the Right Mount
Before you start shopping for any telescope, it is important to think about how you will use it and how much money you want to invest in the hobby of astronomy. Setting budget aside, if you are a newbie and want a beginner's telescope to start, or plan to buy a good kid's telescope, you would pick something very different from, say, a telescope for astrophotography. Luckily, there are computerized telescopes available for a variety of uses at a wide range of prices, and we are here to help you narrow down your choices!
If you’re new to astronomy and just want to take a peek at the sky, an equatorial mount really isn’t necessary. A telescope that comes with an alt-azimuth mount will suit your needs perfectly.
If you are looking to get into astrophotography, take a close look at the payload weight of the telescope mount. Most mounts have a weight capacity. For example, a Sky-Watcher EQ6-R mount has a weight capacity of roughly 40 lbs. However, in general, you want to shoot for maybe 70% of that weight capacity in order not to tax your mount.
Mounts are heavy; they can weigh over 100 lbs all assembled with your telescope and counterweights. Is this something you want to carry outside with you all the time? If not, then maybe consider a small mount. If you do plan to use your mount frequently and you have a heavy setup, consider building an observatory.
Computerized Telescope Mount FAQs
In simplest terms, a computerized telescope is any telescope that uses computer technology, also known as Go-To technology, to find and "go to" a celestial object. Computerized telescope databases include thousands of objects, and depending on the aperture (diameter) of your telescope optics, you can visit a wide collection of huge galaxies, wispy nebulae, and other amazing objects with the simple click of a few buttons.
A “push to” telescope mount is a type of computerized mount that simply tells you where in the sky objects are located. It’s up to the astronomer to point the telescope in altitude and azimuth to the coordinates indicated by the computer system. These types of mounts are more convenient than fully manual mounts, although not quite as convenient as a full Go-To system.
In short, yes - your mount will require some sort of alignment procedure to be able to accurately point towards objects in the sky. Most computerized alt-azimuth mounts, such as the Celestron NexStar series, will require a basic 3-star alignment to create a model of the sky. Equatorial mounts will require first an alignment with the north celestial pole, followed by a star alignment procedure. Some mounts are able to align themselves with plate solving technology, such as the Celestron DX 130AZ.
