Considerations in Choosing a Mount

Payload

Most mount manufacturers list a payload capacity for their product(s). This term (payload capacity) sometimes includes counterweights and sometimes is a bit padded. In general, beware of loading the mount too close to 100% of its stated abilities. For example, if the stated payload capacity is 43 pounds, think in terms of 35 pounds (approximately 80%) maximum for the OTA, camera, and everything else that will be riding on the mount.

Alt-Az vs. Equatorial

There are many opinions on whether one should choose an alt-az mount or equatorial. Alt-az mounts essentially provide a fork in which the optical tube assembly can spin and move on two different axis points. One axis spins from north to east to south to west and is referred to as azimuth. It’s basically spinning a scope on standard compass points. The other axis allows the scope to aim at targets up and down through the height of the sky. This axis is known as altitude. By contrast, equatorial mounts are constructed with one axis being an extension of the earth’s polar axis. Because of the nature of the earth’s rotation on that axis, the stars appear to move in across the sky around that axis, so if the telescope is properly lined up with the poles, the stars circumscribe a smooth circle in the sky aligned around that axis. When it comes to precision tracking, it’s true that EAA is less demanding than astrophotography. However, at the same time, observers should realize that equatorial mounts significantly simplify the movement necessary for tracking an object (keeping up with the apparent movement of objects in the night sky). Alt-az mounts involve constant movement by two motors in harmony. In the case of their equatorial counterparts, because the scope is aligned with the celestial poles of the earth, equatorial mounts only require movement along one axis. As a result, one should know upfront that they will always be simpler to keep on target. That having been said, many EAAers operate effectively with alt-az mounts.

Budget

For EAA-ers starting from scratch, perhaps the first step is to decide on an approximate budget. In the current purchasing environment, a decent EAA rig is going to cost a minimum of $700 if buying used and well over $1000 if buying new.