This is the most advanced version of our most popular diagonal. It was designed by Vic Maris and uses a thick, over-sized mirror polished to 1/10th wave. The mirror has a protective, dielectric coating with 99% reflectivity. It has a compression ring eyepiece tube and the insert tube has a bevel that will better seat the diagonal in the focuser. The FA2 deluxe 1.25" compression ring adapter is included. Both the two inch insert tube and adapter have filter threads. A rubber grip on the 2" tube allows for easy handling in cold climates. The 2" female insert tube on this diagonal will accept 41mm or 1.61" of nose piece length before hitting the built in safety stop. If your 2" nose piece is longer than this specified distance, the nose piece will not fully insert, though this is rarely an issue. The D1040Q adds 4.1" or 104mm to the optical path. These diagonals are assembled, adjusted and double tested at Stellarvue for perfect alignment and performance. The five point cushion system eliminates pinching in all climates and the precision CNC machined components assure perfect alignment that stays that way. The four point adjustment allows us to perfectly align the mirror so every diagonal that leaves here is perfectly aligned.
This new version has additional improvements. It is now made with a low expansion Quartz mirror to maintain optical accuracy as the temperatures drop. The main body is cnc machined from a solid piece of aluminum. The eyepiece and insert tubes are identical to the original non-quartz version featuring a tapered safety on the nose-piece, a brass compression ring on the eyepiece tube and a rubber grip.
Star diagonals are a critical component of any refractor. The performance of an otherwise excellent telescope can be seriously compromised using a diagonal that is misaligned or pinched. We researched diagonal design and fabrication for two years before introducing our first 2” dielectric diagonal. We studied more than 20 diagonals on the market and discovered that 18 of them were either misaligned or pinched! This causes astigmatism and reduces optical performance.
Each diagonal and erecting prism we sell is tested for alignment and will preserve the exceptional quality of your Stellarvue telescope. Since the D1040Q is adjustable, it is the most accurately aligned diagonal we offer.