A 6-inch Dobsonian reflector telescope is just too big and awkward for some people. Finding the storage space in your home is another issue. If you’re looking for a large aperture telescope with a compact design, the Orion StarBlast 6 Astro Reflector Telescope is an excellent alternative. It packs a whopping 6-inch (150mm) aperture primary mirror into an optical tube that fits on a tabletop mount. Its ease of use and portability make the StarBlast 6 a great option for beginners and experienced astronomers alike.
The optical performance of the StarBlast 6 is an improvement over the 130mm tabletop reflectors reviewed in our Best Budget Telescope article. The seemingly small increase in aperture size to 150mm actually offers 33 percent more light gathering ability resulting in brighter and sharper images. Although the StarBlast 6 does have a large central obstruction compared to longer focal length reflectors with similar sized apertures, the reduction in light due to this obstruction should not be apparent to most people. The parabolic primary mirror has a focal length of 750mm and a focal ratio of f/5. Using a parabolic primary mirror eliminates spherical aberration common with low-budget reflectors that have spherical primary mirrors.
Comatic aberration or coma will be present and is typical of Newtonian reflector telescopes. With coma, stars along the edge of the field of view will have a distorted comet-like tail appearance. Stars in the center of the field of view are unaffected. This will be noticeable at low magnification for the most part.
One downside is that the StarBlast 6 costs about $70 more than a 6-inch Dobsonian like the Orion SkyQuest XT6 Classic Dobsonian Telescope, which is arguably better and has a longer focal length. In fact, for an extra $40 you could buy an 8-inch Dobsonian telescope. But again, if storage and portability are a major concern than the StarBlast 6 is good replacement.
The tabletop Dobsonian base is a simplified altazimuth mount that comes pre-assembled for quick setup. The mount rotates 360 degrees and moves up and down with smooth motions. An altitude tension knob can adjust the tension of the up and down movement or lock the optical tube in place. A handy eyepiece rack is built into the side of the mount and can hold 3 eyepieces. Two carrying handles allow for easy portability.
The optical tube attaches to the mount with tube rings. The tube rings also allow you to rotate the optical tube to find a preferred eyepiece angle. By adding a dovetail plate to the tube rings, you could attach the optical tube to an altazimuth or equatorial tripod mount. The front end of the optical tube has a knob that acts as a handle to move the telescope in all directions.
The StarBlast 6 is large enough to operate from the ground if you’re mobile enough or comfortable doing so. However, most people will prefer to place the telescope on a sturdy surface like a picnic table, small portable table, stool or crate.
The EZ Finder II is a red dot reflex sight mounted to the optical tube and used to locate the celestial objects you wish to observe. Unlike a finderscope, the battery-powered red dot finder does not provide any magnification. Looking through the finder’s viewing window you will see a projected red LED dot which is used as a guide to move the telescope until the dot is centered on the target object. Don’t forget to turn off the EZ Finder II when you’re not using it to save battery life.
The telescope comes with two 1.25″ Sirius Plossl eyepieces – a 25mm (30x magnification) and a 10mm (75x magnification). These are good quality eyepieces to get you started but you will likely want to add an additional shorter focal length eyepiece or a Barlow lens to see more lunar and planetary detail. Adding a 4mm wide-angle eyepiece would give you 188x magnification. A 2x Barlow would double the magnification of the included eyepieces to 60x and 150x.
The plastic 1.25″ rack and pinion focuser is perhaps the weak point of the StarBlast 6. It’s decent and does the job but it’s pretty basic. This is something you could upgrade in the future but there is also a slight modification you can do yourself. This archived step-by-step guide details how to remove the standard thick grease and replace it with lithium grease for much smoother focusing.
As with all reflector telescopes, collimation (periodic adjustment of the mirrors) will be necessary. This will make sure the mirrors are properly aligned for sharp and crisp images. While collimating a telescope may seem difficult at first, it shouldn’t take longer than a minute or two once you get the hang of it. And the StarBlast 6 has some helpful features to make collimation easier. The primary mirror is center-marked, a simple collimation cap is included and thumbscrews allow you to adjust the primary mirror with just your fingers. You will need a 2mm Allen wrench to adjust the secondary mirror although one is not provided.
The StarBlast 6 is a great telescope for viewing the moon, planets and deep-sky objects. You can expect to see the craters of the moon; Jupiter including its 4 moons, cloud bands and Great Red Spot; Saturn’s rings, Cassini Division, and largest moon; Mars as a red disk; Mercury and Venus and their changing phases; Neptune and Uranus as tiny colored disks. Under dark skies, the 6-inch aperture will show plenty of deep-sky objects including galaxies, nebulae, and globular and open star clusters.
The combined weight of the optical tube and mount is 23.5lbs (about 10lbs heavier than a 5-inch tabletop reflector) with a 28-inch long optical tube. Compare this to the Orion SkyQuest XT6 Classic Dobsonian Telescope which weighs over 10lbs more at 34.4lbs and has a much longer optical tube at 45.5-inches. The StarBlast 6 is too heavy for a child to move and setup on their own. Teenagers and adults should have no problem carrying the optical tube and mount as one assembled unit or as separate pieces.
Orion also makes a PushTo version of this telescope called the StarBlast 6i IntelliScope for about $160 more. It comes with a computerized object locator that has a database of thousands of objects. A handheld controller provides arrow directions for you to follow to locate and track an object by manually moving the telescope. While this is a nice feature, it’s simply not worth the $500 price tag in our opinion.
Pros and Cons
- Large aperture
- Easy to use
- Excellent for viewing deep-sky objects
- Eyepiece rack
- More expensive than 6″ Dobsonian
- Shorter focal length than 6″ Dobsonian
- Large obstruction