The Optical Tube of Orion Starblast 90
The StarBlast 90 is a 90mm f/5.6 achromatic refractor. At f/5.6, the scope is going to of course have a lot of chromatic aberration, and the StarBlast does so as expected. This means that the scope is in practice limited to rather low magnifications; the images quickly become fuzzy at high powers and of course, the Moon, planets, and bright stars will have ugly purple halos around them. The telescope, unfortunately, has some other optical issues that are a little less expected and a lot more troublesome – the images are just not very sharp even at low powers, which seems to be due to a poor job in manufacture of the lens itself – a wonder, really, since it is kind of hard to mess up a cheap refractor objective. There also seem to be a lot of issues with stray reflections and glare – probably caused by poor interior blackening and baffling.
Unusually, this scope has a lens cap that remains attached when it is taken off of the front. Being held on by a tiny strip of plastic, it’s only a matter of time before it breaks and leaves your cap on the ground, and quite possibly on snow or wet grass.
The StarBlast uses a 1.25” rack-and-pinion focuser. Like many scopes in its price range, this focuser is unfortunately all-plastic. However, the one on the StarBlast is definitely one of the worse ones, as it wiggles a lot as you rack it in and out, which is a real nuisance. Unusually, the focuser also has a bubble level and compass built into it. I have absolutely no idea what it is doing on this telescope, but it is utterly pointless and it would’ve been wise if the manufacturers put the money spent on it into some of the other, more lacking areas of this instrument.
Lastly, the telescope attaches to its tripod with a standard ¼ 20 threaded hole, meaning it’s possible to easily install it on a photo tripod, or bolt a dovetail on to attach it to a real quality astronomical mount (not that that would likely be worthwhile).
Reviewing the Starblast 90’s Accessories
The StarBlast 90 comes with two eyepieces: 25mm and 10mm Kellners providing 20x and 56x respectively, a 45-degree erecting prism, a 5×20 finderscope, and Orion’s MoonMap 260. Orion sells a kit that adds in a 2x Barlow and a dinky red flashlight; don’t bother – the Barlow is good but of no use on such a low-quality telescope and the flashlight is really cheap.
The included Kellners seem to be mostly plastic, and lesser in quality than the kit Kellners often supplied with many inexpensive telescopes. They have a rather narrow field of view (less than 50 degrees) and seemingly internal reflection issues. Despite this, Orion actually makes a point in their advertising to brag about their supposed quality, calling them “quality Kellner eyepieces (not cheapie ‘H’ eyepieces like with most other brands)” when in truth they are not quality and are only slightly better than the Huygens eyepieces included with some of the really cheap scopes on the market.
The included diagonal is a 45-degree erecting prism design. This prism makes for upright and non-reversed images (you can read a newspaper looking through it, unlike a normal star diagonal which will show a mirror image flipped left-right) but at the expense of viewing comfort and image quality. The diagonal not only has a nearly all-plastic build, but the prism induces annoying diffraction spikes on bright stars and planets, and reduces the already-low image quality even further. It really should be replaced by a quality 90-degree mirror or prism star diagonal.
Then there’s the finderscope. A 5×20 finder is already a terribly small instrument – barely able to show you anything in the sky at all – and this one makes matters worse by adding its own miniature 45-degree erecting prism, which gobbles up the finder’s already feeble ability to gather light. What’s more is that the whole finder, including seemingly even the objective, is made of plastic. Thanks to the erecting prism, the finder isn’t even useful as a peepsight, and it attaches to the scope simply via a plastic tab and notch, making replacing it with a new finder quite the hassle.
Lastly the scope also includes Orion’s MoonMap 260, a nice if unnecessary bonus.
The Mount’s Capabilities
The StarBlast 90’s mount is a joke. It is basically a very cheap photo tripod head affixed to a moderately sufficient steel tripod. While the tripod would do an okay job supporting the telescope, in practice the terrible mount head makes the scope’s motions jerky, wobbly, and impossible to fine-tune. There are no slow-motion adjustments, it is never quite balanced, the locking mechanisms are poor and do not allow for anything other than overly-loose motion that makes the scope impossible to keep pointed or alternatively overly tight, jerky movements. If the bad optics and poor accessories didn’t already convince you to avoid the scope, the unworkable mounting should.