Celestron CGEM II 700 Maksutov-Cassegrain Telescope

Celestron 7-Inch Maksutov-Cassegrain Telescope Optical Tube Assembly

The Celestron 7-Inch Maksutov-Cassegrain Telescope Optical Tube Assembly is specifically designed to provide highly detailed, superior contrast views of planets and other small celestial objects. Add this Mak-Cass optical tube to a robust computerized equatorial mount and tripod (sold separately) for close-up views of the Moon's landscape, including craters and maria, as well. For deep sky viewing, the Maksutov design is optimally suited for observing fainter targets such as globular clusters and planetary nebulae. The ability of the 7-inch Mak-Cass to emphasize more celestial object contrast will be greatly appreciated by astronomers viewing from urban areas with higher concentrations of light pollution.

Maksutov-Cassegrain Optical Design

The Mak is a catadioptric telescope, which means the optical design includes both a lens and a mirror. The light coming through a Mak passes through the corrector lens to the primary mirror and back to a spherical secondary mirror before it hits your eyepiece. Images are bright, sharp, and virtually free of chromatic aberration.

The Maksutov-Cassegrain’s optical design offers several unique benefits. Instead of a secondary mirror, the Mak features a 'secondary spot' of reflective coating applied directly to the inside of the corrector plate. Because of this, the telescope does not require frequent collimation like a Schmidt-Cassegrain. Also, the secondary spot is significantly smaller than a traditional Schmidt-Cassegrain secondary mirror, giving the Mak its signature high-contrast views.

StarBright XLT Technology

StarBright XLT is Celestron’s revolutionary optical coating system that outperforms any other coating in the commercial telescope market. There are three major components that make up our StarBright XLT high-transmission optical system design. It features a unique enhanced multi-layer mirror coatings made from precise layers of aluminum, SiO2 (quartz), TiO2 (titanium dioxide), and SiO2 (silicon dioxide). Reflectivity is fairly flat across the spectrum, optimizing it for both imaging and visual observing. The multi-layer anti-reflective coatings are made from precise layers of MgF2 (magnesium fluoride) and HfO2 (hafnium dioxide). Finally, the StarBright XLT uses high-transmission water white glass instead of soda lime glass for the corrector lens. Taken together, these three components make StarBright XLT one of the finest optical coatings available.