Celestron 11" SC RASA astrograph tube 11 inch (279 mm) (Rowe-Ackermann Schmidt Astrograph) RASA telescope is a high brightness telescope designed specifically for astrophotography needs. Due to the short construction length, it is more stable on the equatorial mechanics than longer built tubes of other systems. Celestron's SC RASA astrographs can be fitted with the 11-inch version of the SC RASA by purchasing a special adapter to fit an astronomical CCD camera, or a mirrorless MILC camera or DSLR (digital SLR).
The telescope is so specialized for astrophotography that there is no visual curvature. Its four-lens correction element with a low colour dispersion ED lens element results in an almost completely coma-free and plane-corrected image with no colour aberration, of course. With its huge F/2 aperture, it collects up to 8x more light in a given unit of time than a system with an F/5.6 aperture. The optical design of the Celestron 11" SC RASA astrograph tube allows it to be sensitive to 390-800 nm, covering a much wider range than usual.
The manufacturer has given maximum consideration to the needs of astrophotographers, which is why the telescope has a reinforced precision two-speed (1:10) FeatherTouch focusing eyepiece, which is supported at six points to eliminate the effect of mirror tilt. A built-in 12V cooling fan ensures optimal cooling, while filtered vents allow the mirror to quickly adapt to ambient temperatures. Special mention should also be made of the practical, robust handle on the tube.
The basic accessory is the company's proprietary StarBright XLT coating, which increases the light-harvesting power of the binoculars. When used, the corrective lens has a transmittance of up to 98%, while the main mirror has a reflectance of 95%.
The Celestron tubes are hand-figured and hand-matched, which means that they consistently outperform the optical quality of competing SC tubes in various tests.
