Designed to offer the performance required by discerning astronomers, the Alpine Astronomical Baader ClickLock BBHS Sitall Mirror Diagonal Star Diagonal improves on conventional diagonals through the use of a premium mirror and coatings, along with a ClickLock eyepiece holder.
The mirror is made of Sitall, a crystalline glass-ceramic material that is thermally stable to resist the expansion and contraction that can occur during long astronomy sessions. The mirror is treated with Broadband Hard Silver (BBHS) coatings and sealed with a dielectric coating that boosts reflectivity to at least 99% for minimal light loss throughout its long life. The broadband coatings uniformly transmit all wavelengths of light between 390 and 2000nm for accurate color rendition and enhanced clarity. The surface is optically flat so it will not introduce distortion or other aberrations. As a mirror diagonal, the views through it will appear right side up, but vertically reversed.
Unlike conventional compression ring and set screw holders, the ClickLock system uses three long roller bearings to hold the eyepiece firmly centered in place without marking or marring it, while eliminating the wobble and off-axis tilt. A simple 20° twist locks and unlocks the clamping system for fast eyepiece changes even while wearing gloves. There is no need to fumble with small set screws or for using excessive force and torque to hold the eyepiece in a fixed position. A 2" ultra-hard nosepiece that is made to accept standard 2" eyepiece filters rounds out the diagonal features.