Celestron 7" Maksutov-Cassegrain Telescope OTA - 91012

$1,149.00
Article number: 91020
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  • This 7" f/15 Maksutov-Cassegrain Telescope enables high contrast lunar and planetary views ideal for both planetary imaging and visual applications.
  • Maximum light transmission ensured by premium Celestron StarBright XLT coatings.
  • Package includes 2" visual back, 2" star diagonal and 1.25" adapter, 28 mm wide-field eyepiece, and 8x50 finderscope.

 

This 7" Maksutov-Cassegrain Telescope from Celestron 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" 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

 

Maks are catadioptric telescopes. This means that 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.

 

This optical design provides users with many exceptional features. The Mak has a "secondary spot" of reflective coating applied directly to the interior of the corrector plate in lieu of a secondary mirror. This eliminates the need for frequent collimation as is the case with Schmidt-Cassegrains. In addition, the secondary spot is considerably smaller compared to a conventional Schmidt-Cassegrain secondary mirror, enabling the superior contrast views the Mak is known to offer.

 

An important aspect to note regarding Maksutov-Cassegrain telescopes is that their larger, heavier corrector plates don't cool down and adjust to ambient air temperature as quickly as Schmidt-Cassegrains that have the same aperture.

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:

 

 

  • 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.
  • Multi-layer anti-reflective coatings made from precise layers of MgF2 (magnesium fluoride) and HfO2 (hafnium dioxide). Hafnium - a rare element that costs nearly $2,000 per kilogram - gives us a wider band pass than the titanium used in competing coatings.
  • High-transmission water white glass is used instead of soda lime glass for the corrector lens. Water white glass transmits about 90.5% without anti-reflective coatings; that’s 3.5% better transmission than uncoated soda lime glass. When water white glass is used in conjunction with StarBright XLT’s anti-reflective coatings, the average transmission reaches 97.4%, an 8% improvement.
Model Number
91012
Telescope Series
Celestron OTA
Focal Ratio
f/15
Optical Design
Maksutov-Cassegrain
Telescope Aperture
180mm (7.09")
Telescope Mount Type
No Mount - OTA Only
Type of Electronics
OTA Only - No Electronics
Focal Length (mm)
2700
Optical Coatings
StarBright XLT
Limiting Stellar Magnitude
13.9
Lowest Useful Magnification
67x
Highest Useful Magnification
420x
Light-Gathering Power Compared to Human Eye
661x
Telescope OTA Outside Diameter (in.)
8.75
Telescope OTA Length (in.)
22.5
Telescope OTA Weight (lb.)
19
Warranty
 
Celestron 2 Years
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