Orion SkyView Pro 120mm

4.0 Excellent value, good views, and fairly versatile

- Great Optics
- Stable Mount
- Excellent Price & Value
- Versatile

- Poor focuser
- Poorly balanced OTA (Due to focuser)
- Gear backlash in mount

This is an impressive scope. I have been using this scope for about 4 years now and am pleased with its performance. At almost 5", this achromatic refractor has plenty of light collecting power for serious planetary and lunar observation. And when there aren't any planets high in the sky, you can also point it at your favorite messier objects for excellent deep sky views. I purchased this scope because I prefer the unobstructed crisp views offered by refractors. I also like having the light gathering capability of a large aperture. Usually large refractors commonly cost much more than their compound cousins of similar aperture, but when I came across this one and realized that it didn’t require me to cut off my arm and my leg, I had to have it. The Skyview Pro model comes complete with OTA and beefy equatorial mount. I will detail the attributes of each separately.

--Optical Tube Assembly--
Overall, the optics are great. Stars are pinpoints in the entire field of view. Of course, since it has a standard achromatic objective of modest focal length, there is some CA evident around brighter objects (Jupiter, Sirius, Luna, etc…), but I think it is a fair trade-off for the overall versatility of this scope. Not only can I enjoy planetary views from my light polluted backyard, I can enjoy a large number of deep sky targets as well. Nevertheless, due to the CA, this is not an astro-imaging scope and high magnification on brighter objects usually results in some image degradation. The optics allow for push pull collimation at the lens cell assembly, but mine was very well collimated out of the box.

The 2” rack and pinion focuser assembly is the Achilles heel of this scope and is evidently manufactured to very loose tolerances. It does have two Allen screws that enable the user to collimate the focuser along the y-axis. However, my particular unit has a problem along the x-axis and since there are no screws to adjust for this, the only way to correct the problem would be to modify the focuser/optical tube or replace it entirely. There is also significant gear back lash and image shift when focusing. If you don’t want to waste countless hours trying to make this focuser usable (as I have), I suggest replacing it entirely with one of the inexpensive, (machined) GSO crayfords.

The optical tube is also a little unbalanced with the lighter focuser on one end and the much heavier objective on the other end. A correctable problem since you can push the scope a little further down the tube rings. The only problem with this method is that this will also push the eyepiece closer to the ground and cause you to kneel in order to view objects near the meridian (another reason for switching to a heavier, machined focuser as this will better balance the scope).

-- The Skyview Pro Equatorial Mount--
This mount is solid and is well suited to a scope of this size. You would need a very stiff wind to get a reaction out of this mount, but if it the wind does stiffen, the vibration dampening is about 1 to 1.5 seconds. I got this scope with the optional dual axis drives and they work great for visual use. However, there is a little gear backlash when changing directions. Not a major problem, but backlash means that this mount is probably not well suited for use as an astro-imaging platform. Although this mount doesn’t come standard as a GoTo, there is an upgrade available. This mount also accepts standard dovetail plates so you can use it for all of your scopes (up to about 20 lbs).

For the money, this scope offers an excellent value. Although the focuser is problematic, at this price you can upgrade to a better crafted focuser and still save in comparison to higher end models in this aperture range. The optics are first rate with acceptable (and expected) false color around bright objects. The mount is very well constructed and well matched to this scope. Owners of this scope should expect to enjoy long use and excellent planetary and deep sky views.