Celestron C 700 - 180 mm Maksutov Cassegrain Telescope OTA

Celestron C 700 - 180 mm Maksutov-Cassegrain Telescope OTA

The C 700 Maksutov-Cassegrain telescope is a specialized instrument designed for detailed, high contrast views of smaller celestial objects like the planets.

With the Maksutov-Cassegrain optical tube, this telescope will provide unparalleled views of the planets and up-close views of the lunar surface, including craters and maria, Maks are also well suited to hunting smaller deep sky objects with higher surface brightness, 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.

One important thing to note about Maksutov-Cassegrain telescopes is that the larger, heavier Maksutov corrector plate takes longer to cool down and adjust to ambient air temperature compared to a Schmidt-Cassegrain of the same aperture.

Accessories Included

The CGEM II 700 Mak comes complete with a 2" visual back, a 2" star diagonal with 1.25" adapter, a 28 mm wide-field 2" eyepiece, and a large 8x50 straight-through finderscope. The optical tube accommodates the larger 2" accessories, such as 2" Barlow lenses, the 2" eyepiece and filter kit, and larger wide-field eyepieces.

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 their 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 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.

Astrophotographic results obtained with this telescope on Astrobin

Here you can find some astrophotographs made with this telescope model: Link to Astrobin

Astrophotographic results obtained with this telescope on Astrobin

Here you can find some astrophotographs made with this telescope model: Link to Astrobin

Customer report

Our customer Oliver Stegen has summarized his first experiences with this telescope as a short report:

"Perfect for observing the moon and planets. Clearly outperforms an 8 inch SC in contrast and details, for example in the moon and Jupiter. The special coating of the surfaces of the Celestron is noticeable in a significantly brighter image than the comparable Skywatcher Skymax- 180, which justifies the higher purchase price.The significantly larger dovetail bar than on the Skymax-180 is also positive, as it makes it easier to balance the weight.

For a better overview, for example to have the complete moon in the picture, you should use a good eyepiece larger than 50mm. I use the TeleVue Plössl 55mm for this.

The cool down time is not dramatically above a SC. With closed systems, longer cooling times must always be taken into account. On the other hand, the optics of the Mak are much less susceptible to adjustment. A dew shield is also important to prevent fogging of the optics.

Then you have a perfect instrument for visual observation and astrophotography, especially of the sun, moon and planets."

Many thanks to Oliver Stegen for this helpful report!

Safety informations: PDF Download