Top positive review
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Works Like a Charm, easy to install
on February 8, 2014
Very easy to install, only needs the included hex key. Instructions are clear on where to mount it. Make sure you remove the corresponding (RA) knob on the telescope, or you will break the flexible aluminum motor mount coupler.
Put it on my Celestron PS 127EQ and it tracks Jupiter nicely (with an 8mm eyepiece, i.e. with good magnification). Telescope mount needs to be aligned with the North Star (Polaris) first.
Speed is adjusted with a small knob on the motor unit. For testing I found it tracks Jupiter for more than an hour with barely any adjustments.
Note that the only way to adjust right ascension once the motor is connected is to loosen the r.a. lock nut and then turn the scope manually.
EDIT: I have used it some more, and found it works rather nicely. As I said, you will need to align your telescope mount with the North Star first (polar alignment), at my latitude it is located at a fixed 34 degrees above the horizon. There is a small plastic knob to adjust the speed, and the reason for it is that you need to adjust the speed ONCE only. You are basically setting the angular speed by which it tracks an object in the sky, and that rate (for a given location) is the same for all stars and planets in the sky. It is best to adjust the speed at some higher magnification (say 8mm eyepiece), with a bright object such as Jupiter. This requires a bit of trial and error, watching say one of Jupiter's moons staying at the same distance from the edge of your viewing disk. The next day when you take the telescope out again, you will NOT need to adjust the speed any more.
EDIT 2: Three months have gone by and I still have to change the original battery ... my estimate so far is that one 9V battery will last something like 30+ hrs or use. See the pictures I posted on the right to see how well it works!
EDIT 3: I found that when the battery starts to run low, the speed will inevitably decrease a bit. That means it's time to swap out the battery, so always keep one handy. Of course in my case it happened right when I was trying to take some long exposures of the Andromeda galaxy ...
EDIT 4: Mine has been running for a year now without any issues whatsoever. During that time I went through about 3 9V battery sets, with about a long observation night every one to two weeks. Once in a while there is a star or planet location where that little plastic box is a bit in the way.