| This 90° 2 mirror-type star diagonal has enhanced aluminum mirror coatings for 96% reflectivity. The mirror is overcoated with quartz for long life. The diagonal is designed for refractors with 2 focuser drawtubes, but will also work with Schmidt-Cassegrains by adding optional rear cell adapter #7785C. Optional 1.25 adapter #2715C allows the use of 1.25 eyepieces in the diagonal. A safety stop at the bottom of the 2 eyepiece holder tube prevents 2 eyepieces or 2 Barlows from hitting the surface of the mirror. However, if you use the #2715 1.25 adapter, it is possible that an exceptionally long 1.25 Barlow can project far enough into the diagonal to contact the mirror. Any damage caused in this way is not covered by warranty. The mirror housing and its 2 focuser and eyepiece holder barrels are precision-machined from a single block of solid aluminum, rather than being simply a pair of less-rigid tubes screwed into a flimsy plastic mirror housing or sheet metal stamping, as is the case with lesser diagonals. A solid metal backplate over 4/10ths of an inch thick holds the mirror securely in place to assure permanent collimation of the diagonals parts. The 2 barrel that fits into the focuser or visual back is internally antireflection threaded for higher contrast. It is also threaded to accept standard 2 (48mm) filters. A groove cut into the outside of the 2 barrel acts as a safety stop to keep the diagonal from falling should the scopes visual back or eyepiece holder thumbscrew loosen slightly from cold or use. The 2 eyepiece barrel uses a non-marring soft brass compression ring to hold eyepieces in place, rather than a thumbscrew that contacts the eyepiece barrel directly. This is a very high quality 2 diagonal that is visibly superior in optics and workmanship to the economy and mid-priced 2 diagonals available from telescope manufacturers. It's a worthy upgrade for virtually any Schmidt-Cassegrain, Maksutov-Cassegrain, or refractor that uses a 2 star diagonal. |
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