Review: Orion 12 inch XT dobsonian

After deliberating for several weeks on a scope upgrade, I chose to get an Orion 12 inch XT dobsonian. I selected this scope for a number of reasons: it was the most Aperture I could afford for the money, dobsonian mounts are quick and easy to set up, and I had previously had very good experiences with this vendor (Orion has good customer service). Also, it was on sale because it was from an open box floor model. Ultimately, it seemed the best match of price, performance, and quality that fit within my needs. I ordered it through Astronomics, and, as always, they were very helpful with my questions and the package arrived quicker than expected.

My first thoughts (and I guess I'm not alone in this) was "Wow that's a big box!" But in fact it comes in three boxes: one containing the tube, one containing the primary mirror, and one containing the base assembly. They are bulky but well within ability of an average adult. I feared putting the mirror into the tube because let's face it, if there's one thing to not screw up, it is the mirror. However, this turned out to be much simpler than expected. The base assembly took about 20 or 30 minutes, but might take longer, since in my case, all of the holes were already established because it had been assembled as a floor model. Total assembly took about an hour, with quite a bit of that dedicated to mount the mirror and collimating.

I had been warned that this size solid tube dobsonian could be a lot to handle. It is. I found it difficult to gently place the tube in the cradle of the base, and the jarring certainly didn't help my mirror alignment. In general, I found it difficult to maintain proper mirror alignment which resulted in constant recollimation, but part of this is due to my continued problems with my secondary mirror alignment. The included laser collimator greatly helped with this problem, so even if it got knocked around only a couple of minutes were required to get things back in order. As for carrying it inside and out, I have found a better solution for that. (I'll post pictures and a short write up later).

My impressions for the remainder of this write up are based on two nights of observation. The first night conditions were windy and cold, with a first-quarter moon blowing out most of the sky. The second night both seeing and transparency improved, and moon had moved to third quarter, which gave me four good hours of dark skies.

Mechanically, this scope is a snap to move around. On the first night the bolt holding the base together gave too much resistance when turning the scope, but I loosened it before the second night so that it became much easier to turn. The supplied finder scope is a large right angle version, and while it is much easier to use of the original straight through finders, I did struggle to get used to it. The focusor clearly improved over the old model, and is far more pleasurable to use.

On the first night of observations, I stuck mostly to bright objects. My initial impression set around the number of stars visible. The 12 inch definitely seems to go deeper for those faint stars than in my old model, an original 8 inch XT. Even with the moon out, things looked good. Because the wind continued to pick up, I decided to check out the moon and then called it a night. A word of warning: a telescope this size will produce a painfully (painfully!) Bright image of the moon if set at a lower power without any kind of filter. With a 10 mm plossl, the number of small craters and craterlets really stood out as being significantly more than I had noticed in the past.

With weather conditions much better, and my transportation issue solved with the scope, the second night involved a four-hour observation session focused on hunting down some of the Messier objects I needed for the Astronomical League Messier Observing List. I cruised through Cassiopeia, Perseus, Orion, Taurus, Canis major, Gemini, Hydra, and Monoceros before the moon came up and cold (32°F) sent me packing. I used the two Sirius eyepieces that came with the scope, a 25 mm and a 10 mm plossl , as well as a 2 inch Q70 32 mm eyepiece, and a three element 1.25 inch Barlow. I'll write more on the Q70 another day, in short I ended up using a 25 mm and the Barlow almost exclusively.

My targets included a few nebula, but mostly open clusters. On M1, The Crab Nebula , the view surprised me. With smaller scopes I had had trouble locating this object, even though at magnitude 8.4 it should be visible. With the 12 inch, not only was it easy to find, but it appeared significantly brighter than I would have expected. It actually made me wonder if an optimal observation site with a good weather would allow me to use the scope to pick the Pulsar in its center (although I'm pretty sure that it is far dimmer than the limiting magnitude of this scope) still, that is how pleased I was. Jumping over to the Orion nebula , M. 42 and M. 43, dust lanes seem to flow against the bright background and filamentary detail filled the field of view. For the first time, each of the six stars of the Trapezium stood out, although the F Star winked in and out with the atmosphere. And my last target in Orion also surprised me. M. 78, a reflection nebula north of the Alnitak region, proved difficult for me to find with the scope' s finder, but once there, the offset nebula stood out well as a pair of two tenth magnitude stars stared back at me. Sue French' s book definitely helped find this one. Several open clusters followed, with M. 35 revealing over a hundred stars (estimated) and the intervening NGC 2158 standing out , despite the fact that I did I know to look for it.

Rolling the 12 inch back to its shed, I cannot help but be extremely pleased with the scope. I cannot imagine how I could do better than this for visual observation for $700 (remember, mine was discounted). Even at the regular price, I would still consider a 12 inch dobsonian a great bargain for anyone who focuses on visual observation of deep sky objects. But remember, this is a Large Scope! Hopefully I can have pictures of a poor man's scope buggy up soon.