Telescope Reviews: iOptron Mini Tower

Have experimented with this mount over the last two days and have the following comments:

This is a very good mechanical design. The altitude bearing is smooth and heavy duty. The azimuth bearing appears to work very well also, tolerating a bit of off balance, allowing small telescopes to be used without a counterweight. For a mass produced instrument this is one of the best mechanically.

The levelling screws are a good idea, reasonably well implemented. Anyone who has used a surveyor's transit or total station knows, however, that FOUR screws are far better than THREE, allowing you to level in two directions at right angles to each other, making the task far easier. Still, it is nice to see a company finally making the effort to provide a levelling feature.

The GOTO system with built in GPS works very well. Advertised pointing accurcy of 1 arc minute is a bit over-enthusiastic, but I would say this mount achieves 5 arc minute accuracy 100% of the time, which is quite good. If you level the mount accurately, the one star alignment works fine.

The GOTONOVA system has the advantage of a large display showing many lines of data at once. However, functionally it is not nearly as elegant as Celestron or Meade's on mounts of comparable price and quality. A lot of button pushing is required to go deep into the menu, with no "shortcut keys" available on the handpad.

The ASCOM driver for this sytem works OK with SkyMap Pro, but I have not been able to use it with ACP Observatory control software. I found some workarounds using the Astro-Physics ASCOM driver, which appears to have been cloned for the GOTONOVA system. Hopefully the driver will be revised in future.

Maximum slew rate is about 3.8 degrees per second, which, sadly, is becoming the standard for these types of mounts. I really miss the 6 degrees per second of the old Nexstar single arm mounts. A slew of 180 degrees in azimuth tries my patience somewhat, especially when there is no good reason for not making a faster speed available.

Balance in altitude is somewhat critical. I got an error message stating that the motor was "over current" with my telescope slightly off balance. Balance in azimuth does not appear to be nearly as critical. This may be an issue when switching eyepieces with heavy Naglers and very light short focus eyepieces on a refractor (or switching to a binoviewer).

While this mount works well as a GOTO system, the real tragedy of this design is that it COULD work equally well as a manual "just push it around" alt-azimuth, like the Stellarvue M7, but the encoders appear to be integral to the motors, so when you loosen the clutches and push alignment is lost. If the encoders were separated from the gears, this would be a nearly ideal digital setting circle manual mount at a bargain price. One of the great joys of visual observing for me is to sweep through the Milky Way, "discovering" objects visually, THEN looking them up. A simple glance to the computer screen with a planetarium software connected to a mount with digital setting circles is a great technological advance that, unfortunately, is not available with this mount UNLESS you use the motors only.

In summary, this mount represents a big step forward in a mass produced instrument, but is not perfect. Mechanically, though, for the price it is built like a brick outhouse.