Celestron's Schmidt-Cassegrain optics:
Despite the long focal length of the Schmidt-Cassegrain optics, the tube has a very short design, making the system a compact telescope characterized by extremely light transport characteristics. The light strikes an aspherically shaped Schmidt correction plate and is then thrown onto the spherical main mirror. This reflects it in a secondary mirror, which returns it to the primary mirror. The light beam now passes through the main mirror, which has a central hole. In this way, the light is launched to the focuser located at the rear end of the tube. This means that the system is closed and does not suffer from air turbulence that could harm the image. Of course, this also provides optimal protection against dust. The Schmidt plate is multi-coated, ensuring bright, low-reflection images.
This optic offers a very good image, the contrast and sharpness are convincing and offer great fun, especially when observing the moon, planets or planetary nebulae. Overall, the Schmidt-Cassegrain system is a very good and robust all-round device for observation and photography. The sight at the lower end of the tube allows for easy orientation. The telescope can also be optimally used for occasional terrestrial observations (for example, at close range for bird watching). Celestron SC optics have an aperture ratio of f/10. An optional reducer can be used for astrophotography to make the optics "faster" and increase the field of view.
The main mirror focus ensures a very large focus area, making it possible to fit almost any accessory. Two preloaded ball bearings are used in the positioning mechanism to focus the main mirror to minimize "mirror drift" (a typical problem when using simple bearing shells). The use of high-quality materials, such as CNC-milled components from aluminium, cast steel and stainless steel, ensures high stability with little weight, so you don't need a very heavy mount, as may be necessary with other optical designs.
Optics properties:
long focal length with a short design
light aluminum tube
high quality Starbright XLT multi-coating
system closed
Preloaded ball bearings for low offset primary mirror focusing
The CGEM II mount:
Celestron has updated the popular CGEM mount. Version 2 has a more stable tripod, USB connection, double dovetail clamp for Losmandy and Vixen standards, improved ergonomics and firmware!
What hasn't changed is what has proven itself with CGEM over the years: it's still a serious mount for astrophotography, safely carrying Celestron's SC optics up to an 11-inch (279-mm) aperture. ) for photographic requirements. Of course, you can also combine the CGEM with telescopes from other brands, whether they are medium-sized refractors or Newtonian telescopes. The double saddle clamp is suitable for the two common formats of prism rails (also called dovetail rails). The saddle clamp has two large non-slip screws that can also be easily operated while wearing gloves. Since the clamp presses on the dovetail bar across its full width and not just on the screws, the rail is not damaged during mounting.
Other advantages of the CGEM II:
The tripod legs have markings so you can extend the legs to a consistent length and it's also easy to remember your preferred length.
Built-in Celestron All-Star Polar Alignment to align the mount with the help of any star. So you don't need a polar finder and you don't have to contort yourself to find your way north. You don't even need a clear view of the North Star! The post height adjustment screw is large and easy to grip. This is an important advantage, since the pole height adjustment has to be performed under the load of the optics.
Large database of all popular DeepSky objects, cataloged by name and catalog number; the best-known double, triple and quadruple stars, as well as variable stars and solar system objects.
Permanently Programmable Periodic Error Correction (PEC) - Periodic Screw Error Correction
16-character, two-line LCD hand control with backlit buttons. The hand controller has a USB port for easy connection to PC for mount and hand controller firmware updates.
Tracking beyond the meridian: Up to 30°, so long exposure astrophotography doesn't have to be stopped suddenly.
In Celestron's range of modern equatorial GoTo mounts, the CGEM II sits between the AVX and CGX mounts. We are happy to recommend the budget entry-level AVX, which already has all the benefits of NexStar+ electronics, but is not mechanically designed for large optics. The CGX mount meets the highest demands of astrophotographers, even with heavy equipment. Finally, the CGEM II is an excellent compromise between load capacity, performance and price. It is the workhorse of demanding astrophotographers.
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