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Total 4 reviews
3.8 out of 5 stars
Faster than a speeding Drift-Align
This accessory, which incorporates a nicely etched reticle, can get one reasonably close to polar alignment in a few minutes, with practice.
It must be calibrated first by rotating it against a fixed object (or bright star like Polaris) in order to check the reticles centering. It is a bit fussy to work with, as the 3 stars that you align with in the reticle are hard to place correctly due to the wandering (precession) that occurs. Theres a 10 year gaps in the etched lines that you place these stars in, so one has to do a little guesswork. Scale is not quite large enough to permit pinpoint accuracy.
The construction is adequate. The fit can be sloppy in the polar barrel of the mount, and is subject to wandering. Can be overcome by shimming w/brass or teflon tape. Tightening down on mount barrel is hard to get just right.
Polar Alignment is far better with it than without it, and there are no higher quality polar scopes to be found anywhere at any price. Good enough setup to autoguide on with reasonable care.
Polar Scope good. Illuminator bad!
The good news is that the Losmandy Polar Scope works reasonably well for aligning the mount for visual use. For astrophotography you should still consider drift-aligning, or if available, using your mounts polar alignment utilities. The bad news is the whole arrangement around the reticle illuminator. The issues are the LED device that screws into the polar scope, and the complete lack of a dimmer. The threaded hole to accept the illuminator LED is smaller than what you would normally find on a guiding eyepiece or illuminated finder scope, and the thin wires from the LED to the power pack do not seem to bode well for the illuminators longevity. (Although the LED and wires do seem to be able to stay in a stationary relative position, as one screws the illuminator into the polar scope.) The brightness of the illuminated reticle makes it difficult to see the second and third alignment stars. It would be preferable to see something like the ubiquitous Celestron variable brightness, button-cell illuminator (http://www.buytelescopes.com/product.asp?t=&pid=560&m=) but with a head that can rotate 90-degrees, so it can be left in the polar scope. (The polar scope rotates with the RA axis as the mount moves, so something like the Celestron illuminator might hit the mount - depending on your observing latitude.) One other note: I have a newer GM-8 mount and have not experienced any of the binding problems that you may have heard of in the past.