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Stellarvue Enhanced 2" Dielectric Diagonal - D1029ED


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I’ve been looking at the night sky for about five years now. I am by no means an expert in astronomy, and I consider myself perhaps the most “amateur” of amateur astronomers. One attribute I feel that has been of benefit to me is my understanding of physics and precision devices. With a background in electrical and mechanical engineering, I feel I have a decent understanding of telescope optics and the workings of various telescope accessories. Having said all this, I must say that I do have a fondness for fine optical instruments although my budget doesn’t always cooperate with me. Fortunately, I was able to acquire a pristine, used TeleVue 85 doublet apo refractor early on in my “astronomy career.” Included with the TeleVue 85 was a 2 inch Everbrite diagonal with dielectric coating and 99% reflectivity. Because of the fine performance of these instruments, I have used them as a benchmark for comparison when evaluating other telescopes or diagonals.

As with most telescope “connoisseurs”, I have fallen prey to purchasing another telescope, even though the one I have more than adequately serves my purposes. During a recent promotion at Stellarvue, I acquired a 80 mm triplet apo refractor at a very reasonable price. Stellarvue has a deal where if you purchase one of their telescopes, you are able to purchase, as an option, a 2 inch dielectric coated diagonal, at a considerable discount. Normal price is $189 and with the purchase of a telescope, one can purchase the diagonal for $139. It seemed like a good deal, and I did need another diagonal, so I dipped into some of the ‘09 Christmas present funds and made the plunge.

Needless to say, I have been very delighted with my purchase of the diagonal. The diagonal arrived double boxed, very well packaged with the diagonal sealed in a ziplock bag and wrapped in bubble wrap. There is a small manual, and orange dust cap at the eyepiece end, and a rubber dust cover at the tube end. The housing had a nice black matte finish. There were no scratches and the entire diagonal looked as if it had just come right out of the factory- which it probably did! There is a nice raised clear Stellarvue logo with metallic background along the base of the diagonal. The mirrors appeared intact without any visible scratches or dust. The diagonal had a comfortable weight and felt quite solid. A large textured rubber grip makes it easy to grasp. There is a brass compression ring for the eyepiece and a beveled insert tube which held my Nagler 31 very securely- even with the scope at zenith. Included is a 1.25” adapter which also has a brass compression ring which held my Panoptic 15 very nicely.

So, it looks and feels nice, but how are the optics? According to Stellarvue’s product description, the diagonal features a thick, oversized mirror with 99% reflectivity. In addition, the mirror is housed in a CNC housing with carefully selected adjusters to maintain mirror alignment after factory testing and adjustment. Cushions reportedly prevent mirror pinching.

I was able to take both the Televue 85 and the Stellarvue 80SVT, with their respective diagonals, to a semi-remote area in central Washington for a short night of viewing. I tried each diagonal on the Televue 85, then on the Stellarvue 80SVT. I paid particular attention to contrast and the number of stars I could discern at the periphery when viewing the Pleiades. I really could not detect a difference and was able to visualize the same stars with little, if any light scatter. The stars, to me, appeared equally visible with either diagonal. There were nice comparable views of M81 and M82 with nice dark backgrounds, and detail was sharp on the bands of Jupiter.

Anecdotally, when I first received the Stellarvue diagonal and was taking it out of the box, I reached for my ringing cell phone with my left hand, and somehow lost balance with my right hand, dropping the diagonal onto a hard linoleum kitchen floor. I thought: “This is it. I’ve destroyed the diagonal without even getting a chance to use it.” However, inspection revealed not a single scratch and the mirror appeaerd to be unscathed. Function was evidently unaffected and the mirror alignment probably unchanged from when it left the factory. Don’t go testing your diagonals by dropping them on your kitchen floor. I hope it never happens again. But since it did, and since it did not appear to affect function of the diagonal, I am convinced that this diagonal is one rugged workhorse.

In summary, I think that for the package deal price of $139, the Stellarvue 2 inch dielectric diagonal is an excellent buy. It is well made, solid, and functions just as well as other diagonals costing twice as much or more. With the Stellarvue brand, you are guaranteed uncompromised attention to detail and emphasis on achieving optical excellence. Even at the “normal price” of $189, I would buy this diagonal again….if I were ever to acquire another scope.

Disclaimer: I have no association with TeleVue or Stellarvue. I just enjoy their nicely crafted products and friendly customer service/support








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