by Ed Seward
First a little background to help evaluate this review…
I started looking for a new telescope to replace an ancient 4 ¼ Newtonian with an equatorial mount. My eyes drifted to those numerous wonderful goto scopes. But then I thought about how often I would be doing any photography. I also needed a telescope that was readily portable, fairly easy on a bad back and fit in a typical size car. This moved Dobs to the top of my list as I saw little if any photography in the foreseeable future. The Sky & Telescope reviews of the Orion XT telescopes quickly moved them to the top of my list. I was then very lucky that NOVAC had a public session at Mason Neck. One of the NOVAC members brought his Orion XT10 to that session. As with every other NOVAC member I have met he was very willing to allow others a look through the eyepiece, and a great willingness to answer questions. That night confirmed the XT10 as the scope for me to order. In the two and a half months since getting the XT10 I have taken it out about 20 times and been extremely happy with it.
There were two other things I learned about that night at Mason Neck: Telrad finders and the Company Seven store in Laurel. There are two options for many of us to get Orion XT telescopes. The obvious method is to order directly from Orion. For those that want someone else to check and align the telescope optics and assemble it, Company 7 will do that for an additional $100. I chose to order directly from Orion. The optical tube assembly (OTA) with viewfinder, eyepieces arrived in one box. The wood and hardware for the base were in another box. (By the time the telescope arrived in mid-October, I had also purchased a Telrad and an Orion collimating eyepiece.) The OTA came double-boxed and arrived in good shape.
The first thing I did was use the collimating eyepiece to check the alignment. I was pleasantly surprised that the primary mirror just needed one screw nudged. The slight turn required was extremely slight. The primary mirror had picked up some dust along the way but was not yet to the point of requiring cleaning.
One problem I had with assembling the scope was with the finder scope that comes with the XT10. The assembly was rolling right along and the parts list does not mention an O-ring but the text portion does. The O-ring comes wrapped around the finder mounting bracket. Watch out for that O-ring and everything should go smoothly.
I found the instructions for assembling the base to be easy to understand. Before assembling the base, one should their fingers over the seven white pieces of Teflon stapled to the various pieces. This is to make sure one cannot feel the staples.
This is a good time to point out that I found that when I used the XT10 with magnifications greater than 240, the azimuth or horizontal motion was too jerky. The vertical motion is perfect.) But then there are the Sky & Telescope modifications for Dobs (Teaching an Old Dob New Tricks, Sky & Telescope August 1998, p125). Since the XT10 already comes with Teflon pads, I went with a modified solution. I separated the two main portions of the base (by removing the nut on the central bolt). As usual for the Sky & Telescope mods I made seven big washers (mine are about 3 inches in diameter) and placed six of them on the central bolt. (Picture of the six washers in place.) To try something different in search of smoother movement, I placed two 1 inch Magic Sliders on either side of the three Teflon pads on the bottom base piece. The Magic Sliders are only about $6 at Home Depot. If you choose to do this, make sure the Magic Sliders are no closer to the central bolt than the Teflon pads so as to clear hardware on the other rotating piece of the base. Since the Magic Sliders are thicker than the Teflon pads, I played it safe and left the Teflon pads in place in case I decided to pry out the Magic Sliders. (Picture of the six Magic Sliders in place.) Anyway, once the Magic Slider pads and six milk carton washers are in place, place the upper portion of the base back over the central bolt. Now, place the seventh milk carton washer on the central bolt and tighten the nut in place again as appropriate. Since making this modification, I have found the azimuth/horizontal motion of the XT10 to be great.
While carrying the telescope around I move it in two pieces: the tube (weighs about 30 pounds) and the base (weighs about 25 pounds). The 47 ¼ inch long tube fits well in the backseat of the car. The base fits in the trunk as long as one has an area 23 inches high. There is a handle on the base explicitly for the purpose of making it easy to carry.
The dovetail bracket on the 9×50 finder scope is easy to place in the dark. For correct vertical/altitude movement, the XT scopes use two springs. When not in use I leave them loose, but during setup they are very easy to correctly attach in the dark.
In this latest version of the XT10, the following features are new:
- Four vane spider (previously 3 vanes)
- Center mark on the primary mirror
- Fully collimatible two inch focuser with 1 ¼ adapter (The focuser was not previous collimatible.)
- Movement knob near the front of the tube. (Nice but not a big deal.)
- Pyrex primary mirror instead of glass.
- Now comes with 10 mm (120x mag) and 25 mm (48x mag) Plossl eyepieces
- 9×50 finder scope instead of 8×50
For me the telescope has performed very nicely. I have been extremely happy when looking for deep sky objects. When looking at Saturn in the early evening, polar darkening and one equatorial band have been readily visible. The moons Titan, Iapetus, Dione, Rhea and Tethys have also been readily visible.