TRG – Telescope Review Guide

Orion’s Skyquest XT4.5 is the smallest in their Dobsonian line of telescopes that includes the XT6 , XT8 , and XT10. Newcomers to the hobby are always surprised at how large amateur telescopes are, but to experienced observers, this XT4.5 is considered a very small scope. Tiny, in fact (It’s so small, astronomers are buying them just because they think they’re so cute). Make no mistake, though–the XT4.5 is a full-fledged telescope, and is a serious observing tool that could last you for years.

Your money buys you a lot in this case. Included are a good-quality 4.5″ f/8 primary mirror, two eyepieces, a finder, and a CD-ROM with a stripped-down version of The Sky, a software guide to the sky. The scope comes in two cartons. One contains the optical tube, and the other is a flat-packed box containing the base, which you assemble yourself. Orion includes all the hardware and tools you need, and the instructions are well written. Allocate about 30 minutes to assemble and align everything.

There are a couple of cost-cutting measures. The primary mirror is spherical, not parabolic (this is not likely to affect the views, however). Also, the focuser is plastic. Plastic focusers are naturally less robust than metal ones. Finally (and this may be the most serious concern of all), the scope is a little short for an adult. The eyepiece is only 3 feet off the ground, which may force you to stoop over (hint: try sitting on a short chair or stool while observing). On the other hand, the height is ideal for a child, making this a great telescope for kids.

Under the stars, the XT4.5 exhibits excellent performance. Once properly collimated (aligned), the optics give clear, sharp, contrasty views.  Jupiter’s cloud band and four moons are no problem to see, nor are Saturn’s rings. The Orion Nebula is a glowing fan of green gas, with a quartet of tiny stars at its core. Under dark skies (and with some diligence) the XT4.5 can even pull in some of the fainter deep sky objects, like the brighter galaxies in the Virgo Cluster.

As recently as a few years ago, the old adage regarding telescopes was that you must spend at least $300 to avoid buying junk. While this is still mostly true, Orion’s little XT4.5 breaks the price barrier in a big way. As long as you can deal with the short eyepiece height, it’s a great starter scope.

The Orion SkyQuest XT8 is a marvel of simplicity. It makes for a great first ’scope for beginners, it was in fact MY first ’scope, as well as an advanced ’scope for more experienced star gazers. What makes this such a wonderful telescope?

The Mirror

The  Orion SkyQuest XT8 has a huge 8″ mirror. This gives it 73% more light gathering ability than a 6″ mirror. More light means the more objects you can view, you can view more distant objects, and you can see finer detail in near space objects. You haven’t lived until you’ve actually seen the rings of Saturn on the Great Red Spot of Jupiter first hand!

The Base

The  Orion SkyQuest XT8 comes with a Dobsonian base with Orion’s CorrecTension spring system. What this means is you don’t waste any time setting up and aligning your telescope. You set the base on the ground and set the optical tube assembly on the base, hook up the CorrecTension spring system and you’re ready to begin viewing! Just point the telescope in the direction you wish to view and start viewing. When you wish to look somewhere else, the telescope is easily re-aimed by pushing or pulling the tube to point at the new object. The CorrecTension spring system provides just enough tension to keep your telescope oriented where you want it yet doesn’t require a lot of force to move the telescope in a new direction.

Lightweight

The  Orion SkyQuest XT8 is fairly light weight, weighing in at 42 pounds for the tube and the base combined. This is important because if a telescope is too heavy then you aren’t going to use it very much.

Versatility

The  Orion SkyQuest XT8comes in two models – the classic, which is the one I have, and the IntelliScope. The Intelliscope comes with a computerized object locator with over 14,000 sky objects to help you find and identify objects.

Next to last in my 6 part series on choosing your first telescope.

Telescope mountings

In the first four parts, I’ve discuse aperture, power and the different types of telescopes. Now I’d like to talk about an often overlooked but very important aspect of using a telescope – the mounting. A shaky view is all it takes to a fanatastic viewing session! A good mount can enhance your views. There are two basic telescope mountings:
ﾷ The equatorial and
ﾷ The altazimuth.
An equatorial mount is designed so you can easily track the motion of the sky as the Earth turns and its motions indicate celestial directions in the eyepiece. This helps when you’re trying to find your way among the stars with a map. The altazimuth mounts are simpler and just swing up, down, left and right. You have to move the scope along every so often to follow the stars, moons and planets. An altazimuth mount is both cheaper and lighter for the same degree of stability.

Come back for my concluding article when I’ll wrap everything up.