GSO 6" Ritchey-Chretien Astrograph Telescope

Ritchey-Chretiens deliver images with very little distortion. They have a flat field of view, so objects are in sharp focus right to the edge of the image. The image is coma-free, so stars at the edge of the field of view remain perfectly round. And there is no false colour because they use only mirrors with no correcting lens. 

The 6" f/9 design provides enough aperture and a long enough focal length to give good image scale. It is ideal for smaller deep sky objects such as planetary nebulae, galaxies and small globular clusters. 

GSO mirrors are made from optical quality BK7 glass and are limited only by diffraction, which means they achieve the theoretical maximum resolution possible for the size of the mirror. They are machined and polished to better than 1/12 wavelength, sometimes 1/16 wavelength, which is considerably better than the industry norm. The 99% reflective dielectric coatings are greatly superior to alumunium coatings on some other mirrors. Each mirror is individually tested and hand-corrected if necessary after production, with final testing by laser interferometry.  

The open tube and in-built cooling fans enable the telescope to cool quickly, with virtually no problems with dew. A computer-optimised baffle system minimises any stray light in the tube.  

Optical tube assembly only. Comes with a 2" Crayford focuser, a Dovetail Plate and 25mm and 50mm extension tubes.