S & T Test Report Alan Dyer Celestron's Superfast Astrograph Celestron's update of the Schmidt astrograph delivers super-sharp images across an expansive field. Is there a catch? Deep-sky photographers are a demanding lot. We'd like sharp optics with enough focal length to provide good detail in our deep-sky targets. But we also want wide fields for impressive images filled with nebulosity and stars. Oh, and we also want fast focal ratios, to keep exposure times short. And can we please have no star-distorting aberrations at the corners of the frame? Celestron's new Rowe-Ackermann Schmidt Astrograph is designed to deliver on all those potentially conflicting counts. Think of it as a massive 620-mm-focal length "lens" with an astonishingly fast f/ratio of just f/2.2. The Rowe-Ackermann Schmidt Astrograph US price: $3,499.95. Available from celestron.com and through dealers worldwide. WHAT WE LIKE: Pinpoint edge-to-edge star images Fine focusing control WHAT WE DON'T LIKE: Significant vignetting with DSLRs Required T-rings not supplied Celestron's Rowe-Ackermann Schmidt Astrograph is a reconfiguration of its 11-inch telescope into a design dedicated to imaging at its f/2.2 prime focus. Unless otherwise noted, all photos are courtesy of the author. 66 June 2015 sky & telescopehttp://www.celestron.com