Celestron CGEM II 700 7-Inch Maksutov-Cassegrain Telescope Optical Tube Assembly

MFR: 91012
SKU: 91012_FCA-VG

Starting at $106/mo

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In the box

Celestron CGEM II 700 7-Inch Maksutov-Cassegrain Telescope Optical Tube Assembly

  • Celestron CGEM II 700 Maksutov-Cassegrain Optical Tube Assembly
  • 8x50 Straight Through Finderscope
  • 2-Inch Visual Back
  • 2-Inch Star Diagonal
  • 2-Inch to 1.25-Inch Adapter
  • 2-Inch Eyepiece: 28mm (96x Magnification)
  • CGE Dovetail Plate

From The Wavelength Blog Read more

Celestron CGEM II 700 7-Inch Maksutov-Cassegrain Telescope Optical Tube Assembly

The Celestron CGEM II 700 Maksutov-Cassegrain Telescope Optical Tube Assembly is a specialized instrument designed for detailed, high contrast views of smaller celestial objects like the planets. This Maksutov-Cassegrain optical tube provides unparalleled views of the planets and up-close views of the lunar surface, including craters and maria, and is also well suited for hunting smaller, fainter, deep sky objects such as globular clusters and planetary nebulae. Astronomers located in urban areas will appreciate the Mak’s ability to bring out more contrast in celestial objects.

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.

Celestron CGEM II 700 Maksutov-Cassegrain Optical Tube Assembly

  • Optical design: Maksutov-Cassegrain
  • Aperture: 180mm (7.08-inch)
  • Focal length: 2700mm (106.3-inch)
  • Focal ratio: f/15
  • Focal length of eyepiece 1: 28mm (1.1-inch) 2-inch eyepiece
  • Magnification of eyepiece 1: 96x
  • Finderscope: 8x50 Straight Through
  • Star diagonal: 2-inch with 1.25-inch adapter
  • Optical tube: Aluminum
  • Highest useful magnification: 420x
  • Lowest useful magnification: 67x
  • Limiting stellar magnitude: 13.9
  • Resolution (Rayleigh): 0.64 arc seconds
  • Resolution (Dawes): 0.52 arc seconds
  • Light gathering power (Compared to human eye): 661x
  • Secondary mirror obstruction: 40mm (1.57-inch)
  • Secondary mirror obstruction by diameter: 22%
  • Secondary mirror obstruction by area: 5%
  • Optical coatings: StarBright XLT
  • Optical tube length: 571.5mm (22.5-inch)
  • Optical tube diameter: 222.25mm (8.75-inch)
  • Optical tube weight: 19 lb (8.6 kg)
  • Dovetail: CGE Dovetail Bar

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