There are only a couple of basic types of telescope mountings, although there are variations of each.
An equatorial mounting has one axis aligned parallel to the axis of rotation of the Earth by pointing it at the North or South celestial pole. Then, to compensate for the Earth's rotation, the mount and telescope are moved in this axis, usually with a motor that turns the mount at the same rate as the Earth's rotation. This axis is called the polar axis. The other axis on an equatorial mount is called the declination axis. This axis allows movement of the scope at right angles to the polar axis. Movements in these two axes together permits aiming the scope at any part of the sky. Once an object is found, both axes are locked down, and just the polar axis turns to track the object. Most non-equatorial mountings have two axes that allow pointing in any direction, but require movement in both axes to follow the stars. The azimuth axis moves the telescope horizontally, and the altitude axis move the telescope vertically. The most simple type of non-equatorial mounting is the altazimuth mounting. Altazimuth is a contraction of altitude and azimuth. A Dobsonian telescope is an example of a kind of altazimuth mounting. With this manual non-equatorial mount, you track the stars by pushing the telescope by hand with movements in both altitude and azimuth at the same time. It's virtually impossible to take time exposures through the telescope with an altazimuth mount that is pushed by hand. There are also computerized altazimuth mountings. Many of the popular computerized Go To telescopes are of this design. The scope still moves horizontally and vertically, but each axis is motorized and the movements are controlled by a computer. Such a mounting can track the stars as they move across the sky to compensate for the Earth's rotation, and keep a star or planet centered in the eyepiece for observation. But because of the geometries involved, the rest of the field in the eyepiece or camera will rotate around the center of the field of view. This is no problem for visual observations, but greatly limits the length of exposures that can be taken with this kind of mounting for astrophotography. Even an altazimuth mounted Dobsonian can be driven by computers and motors on each axis, essentially motorizing it and turning it into a Go To mounting that can follow the stars, but it will suffer from field rotation. A Dobsonian can also be placed on an equatorial platform called a Poncet platform that is named for it's inventor, Adrian Poncet. This platform has a conical section that allows it to track like a polar-aligned equatorial mounting, although the maximum amount of tracking time is limited before it has to be reset.
If you don't already have a telescope and mounting, and you want to seriously pursue astrophotography, you should consider getting a German-equatorial mounting. If you already have a telescope on an equatorial mounting and you know how to correctly polar align the mount, you can let the camera and lens ride piggyback on top of the telescope and shoot longer-exposure wide-field photos. The requirements in terms of accuracy of polar alignment and tracking are much less for wide-angle astrophotos. Importance of the Quality of the Mount
If you think that astrophotography is a hobby that may last you for a while, it is better to save up your money in the beginning and wait until you can afford a good starter mount. If you initially buy an inadequate mount, you will quickly become frustrated with its deficiencies. Beware the "department store" telescope! There are any of a number of telescopes, some even made by reputable manufacturers, that are sold in department stores that cost a couple of hundred dollars and promise high magnifications, and may even offer computer Go To pointing. It's not that these scopes are trash, they may be a decent bargain for the money for visual use by a beginner, it's just that they are not suitable for almost any type of astrophotography. Starter Mounts for Astrophotography The term "inexpensive" has a different definition for everyone, but good, inexpensive German-equatorial starter mounts for astrophotography with telescopes are difficult to find for less than about $1,000. This may seem very expensive considering that you can get completely computerized telescope, like a Meade 80mm Autostar Go To computerized refractor for $300. Unfortunately, you really won't be able to take pictures of anything except the moon with it. The problem with most of these inexpensive computerized mountings is that they are not really designed for the rigors of astrophotography, and they are almost universally of altazimuth design. There is nothing inherently wrong with an altazimuth mounting, it can track the stars very well for visual use. The problem is that because it is not an equatorial mounting that allows the polar axis to be aligned with the Earth's axis of rotation, long exposure photographs will suffer from field rotation. Inexpensive equatorial mounts are available, and while they may be acceptable for visual use, unfortunately they are not very good for astrophotography.
Really Bad Cheap German Equatorial Mounts There are some really bad mounts out there that are so inexpensive you may be tempted to consider them for astrophotography if you are on a really tight budget. Do yourself a favor and stay away from any really cheap mount for astrophotography. If you are really serious about astrophotography, you will also want to look for a German-equatorial mount, and not an altazimuth mount. The simple hard truth of the matter is that you won't find a good mount for astrophotography with a telescope for less than about $700 new. You may be able to find one of these for considerably less if you buy it used on Cloudy Nights or Astromart. You can also get away with a much less expensive mount if you only want to shoot with short focal-length camera lenses. It should come as no surprise that you get what you pay for. If you can not afford a good mount, don't waste your money on a cheap mount. Build yourself a home-made barn-door mount instead, and save your money until you can get a good mount. An Inexpensive Do-It-Yourself Alternative: The Barn-Door Mount If your budget is extremely limited, consider a simple, home-made, manual "barn-door" mount. It can be easily polar aligned and it will hold your camera and wide-angle lens and allow exposures up to several minutes. Gary Seronik also has an article on how to build a motorized tracking platform with a curved plastic-bolt design. You will have to built it yourself, but it takes minimal skills, works great, and is very inexpensive. Commercial Barn-Door Mounts If you don't want to make a barn-door mount yourself, and portability is more important that cost, you can purchase the commercial equivalent of a barn-door mount. AstroTrac makes sophisticated, but expensive, tangent-arm equatorial drives that will hold a fairly substantial amount of weight. This device runs on 12 volts. Originally it was made to hold a camera with camera lens and fit on a camera tripod. Now AstroTrac has models that come with their own dedicated tripod that will hold a small telescope. If you are traveling overseas and portability is your primary requirement, this is a good device to look at. Mini Camera Tackers iOptron and Vixen also make a very small equatorial tracking device that will hold a camera and camera lens on top of a camera tripod. These devices are very compact and come with a polar-alignment scope. The iOptron SkyTracker weighs 2.6 lbs (1.2 kg) without batteries, and is about 6" x 4" x 2" (153 mm x 104 mm x 58 mm) in size. iOptron says it can carry a camera and lens up to 7.7 lbs (3.5 kg). The Vixen Polarie Star Tracker is a similar design to the iOptron SkyTracker, but the polar scope costs extra. It weighs 1.4 lbs (0.64 kg) without batteries, and is about 3.7" x 5.9" x 2.3" (95 mm x 137 mm x 58 mm). Vixen says it can carry a camera and lens that weigh 7 lbs (3.175 kg). A well-made, robust, home-made barn-door tracker can work just as well as these devices at a fraction of the cost. But if money is no object, they are neat little devices for use with wide-angle and short telephoto lenses. Inexpensive German Equatorial Mounts There are motorized German equatorial mounts out there available for less than $1,000, such as the Orion SkyWatcher EQ5 , and the Meade LXD 75, and Celestron CG-5. I do not recommend any of them as an investment for serious long-exposure, long-focal length deep-sky astrophotography. I recommend saving your money for a better mount. While some may be adequate for visual use, they are usually inferior for long-exposure astrophotography, particularly at prime focus with long focal lengths. They may be usable for piggyback photography at short focal lengths. If you already have one of these mounts with your scope, then certainly try it and see how long of a focal length you can use. In addition to the less-than-superior mechanical construction and design on most of these inexpensive mounts, a major weak point is usually their tripods. In an effort by the manufacturer to save money, the tripods usually suffer, and so will your attempts at long-exposure, prime-focus astrophotography. Please note that just because I don't have a very high opinion of these inexpensive mounts, that doesn't mean it's not possible to use them for astrophotography. I tend to be a perfectionist and view things very critically. For any of these mounts, I am sure you will be able to find someone who has used them successfully and produced good pictures. The problem is one of usability and investment. You may have to really tinker and fight with the mount to get it to work. Personally, I think you would be much better off taking the money you would put into an inexpensive mount and saving it and investing it in a good mount. A couple of mounts from Synta, made in China, are getting pretty good reviews as reasonably priced solid platforms for beginner astrophotography. They are sold by Sky-Watcher in most of the world, and branded by Orion in the United States. The Sky-Watcher HEQ5 Pro / Orion Sirius is a good small basic mount that is rated for a payload of about 13.5 kg or 30 lbs, although it is a good idea to divide these numbers by 2 for astrophotography. A bigger brother is the Sky-Watcher EQ6 Pro / Orion Atlas EQ-G Mount The iOptron EQ45 is another relatively inexpensive mount in this price/performance class that is worth taking a look at. You do not absolutely need a computerized Go To controller that will automatically find objects. However this is a very nice feature to have if you can afford it. There is also an EQMOD which allows a computer planetarium program to interface with these mounts and give Go To control from the software. The latest versions of these mounts also have a direct interface for an SBIG-ST4 compatible autoguider plug.
Good German Equatorial Mounts
Portable mounts include the Losmandy GM-8 and GM-11; the Astro-Physics Mach1GTO; the Takahashi EM-200, and the Orion Atlas EQ-G. The Losmandy GM-11 is one of the best reasonably priced mounts for the money. It can carry a serious payload and is extremely rigid and can track fairly accurately. Losmandy offers the Gemini Go To system for the GM-8 and GM-11 mount, but it is a fairly expensive option. Astro-Physics makes an decent series of mounts that have Go To designed into them, but they are expensive for their price-performance ratio. Takahashi makes a good series of mounts, but requires a computer to use the Go To functions, and are also expensive. The Orion Atlas (Sky Watcher EQ-6 Pro) is a decent entry-level mount with Go To at a good price that will carry a reasonable payload, but is not quite the same quality as more expensive mounts. The iOptron iEQ45 is a similar option. These mounts can also usually be found used on Astromart or Cloudy Nights.
Sturdy Tripod or Pier Almost as important as a decent mount is a good sturdy tripod. Everything that happens through the telescope is based on the stability of the mount and tripod. Many a decent mount has been compromised by a less-than-solid tripod. Successful astrophotography is based on a chain of components and is always critically dependant on the weakest link. Most of the tripods and piers for the above mounts are well made, solid and sufficient for portable use. The Losmandy mounts come with a tripod, others have to be purchased separately. Most of the tripods and piers listed below can be used with other mounts by the purchase or construction of an adapter.
*Prices and availability of all items are subject to change without notice by the vendors and manufacturers. |
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. It is rated for a payload of 18 kg or 40 lbs, but again, it is a good idea to divide this by two for astrophotography. 
(Sky-Watcher HEQ5 Pro) (Made in China).