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.

Sporting the classic long-tube Newtonian design, the Orion SpaceProbe 130 mm provides great all-around viewing performance. One minute you can be studying lunar crater formations at high power; the next, the ethereal glow of a nebular star factory. A few minutes later, the ringed visage of Saturn. All served in crisp detail by way of the Orion SpaceProbe’s light-gathering 130mm (5.1″) primary mirror of 900mm focal length (f/6.9).

The Orion SpaceProbe 130 ’s mirror lies at the base of the rolled-steel optical tube, which is outfitted with a smooth rack-and-pinion focuser. The Orion SpaceProbe 130 accepts 1.25″ eyepieces, including the two fully coated Explorer II eyepieces that come standard with the SpaceProbe 130mm: a 25mm for low-power viewing at 36x and a 10mm for higher-power looks at 90x. Also standard is a 6×30 achromatic finder scope to help home in on celestial targets.

The Orion SpaceProbe 130 comes on the sturdy EQ-2 equatorial model, with adjustable aluminum legs and accessory tray. Slow-motion controls allow fine manual pointing of the telescope and easy star tracking. Addition of an optional EQ-2M AstroTrack electronic drive enables the telescope to track objects automatically.

 The Orion SpaceProbe 130ST

The Orion SpaceProbe 130ST is a step up from the SpaceProbe 130 for the more serious beginning or intermediate stargazer who wants additional performance, particularly for targeting deep-sky objects.

The Orion SpaceProbe 130ST is indeed more compact than the standard Orion Space Probe model. The Orion Space Probe 130 ST’s optical tube measures 24″ long compared to 33″ on the standard Orion Space Probe 130. The focal length of the Orion Space Probe ST’s 130mm (5.1″) primary mirror is 650mm (f/5), yielding a wider field of view and brighter images for a given eyepiece focal length.

The Orion SpaceProbe 130ST has a primary diffraction-limited parabolic mirror, the same type used on much larger reflectors costing many times as much. On a short-focal-length design like this one, a parabolic mirror is a must for focusing incoming light to a point and delivering sharp, detailed images. Moreover, the secondary mirror of the Orion SpaceProbe 130ST is held in an advanced holder with thin 0.5mm metal vanes, to reduce diffraction spikes and light loss. These features combined with the included 25mm (26x) and 10mm (65x) Sirius Plössl eyepieces and quick-release 6×30 achromatic finder scope make this one sweet optical system for astronomy! It also includes a collimation cap and center-marked primary mirror for easy optical alignment.

The Orion SpaceProbe 130ST comes on an EQ-2 equatorial mount with dual setting circles and slow-motion hand controls. An optional EQ-2M or AstroTrack electronic drive can be added for automatic tracking. The adjustable aluminum tripod is strong yet lightweight and includes an accessory tray.

Whether you’re looking for a better-quality first telescope or a portable instrument to complement your big Dob, you’ll love the Orion SpaceProbe 130ST.

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.