Orion Skyquest XT12i Dobsonian
I purchased this scope about 2 weeks ago. I disassembled the mirror cell, redrilled the holes on the 9 point flotation pads
and loosened them enough to actually work. Before this the triangular pads were pretty much locked in place - very stiff.
I then released the mirror hold down clamps - looks like (at least the one I have) they put the wrong hold downs on this mirror - too short, causing excessive strain on the mirror. I cut them down for minimum diffraction , set the tension correctly and reassembled. I mention this mainly because after making these adjustments, I was very surprised at what I saw through the eyepiece at first light.
I've seen and evaluated a lot of optics. This is the first newtonian (including an Optical Craftsman 10" f/7 and a Galaxy 12.5" f/4.8) which has such a perfect star test that I have yet to identify any faults. I'm still waiting for a near perfect night, but even in so - so seeing, the images through this scope are impressive. Last night the Moon was just past half phase and high in the sky which helped seeing a bit. Turbulence was quite evident and caused high speed blurring of fine surface detail. Even so, 400x was usable with literally hundreds to small craters visible in the area of Copernicus. I think ,in near perfect seeing, 800x would show even more fine detail.
I have seen enough variance in optics over the years to realize that this one may be a fluke, but I'd like to give whoever made this mirror a bit fat kiss right on the lips.
If you purchase one, have someone knowledgeable make those mods and adjustments - If you are lucky, you may just find that your average mirror becomes a great one like mine !

Overall Rating: 10
Optics:10 Mount:8 Ease of Use:10 Value:10
Weight: 1 (Unreliable Vote)
Date:
By: Anonymous (xxx.xxx.49.226)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=500931

Reply
I have a 12XTi that with modest modifications (tube flocking, blackening the edges of the secondary mirror, obtaining a helical fine focus adapter and installing a cooling fan for the primary), throws up some of the best reflector images I have ever seen from any reflecting telescope, bar none.  At around $1,100 with digital setting circles thrown in, the 12XTi is a fantastic steal.  Mechanically it's a bit flimsy.  The OTA is too heavy for the thin side boards which causes too much lateral flexure.  The 10XT is extremely solid by comparison.  The mount for the 12XTi is under built.  It's not as smooth axially as any of the high end Dobsonians (Obsession, Starmaster, etc.).

Not an heirloom by any means.  It's not a scope you'll be handing down to your grand children one day, but optically to use and enjoy for the next several years it's wonderful.

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