Outfitted with an over-sized aperture, long effective focal length, and their proprietary StarBright XLT optical coatings, the Celestron C11-A XLT 11" f/10 Schmidt-Cassegrain Telescope provides power and portability. The coating system consists of anti-reflection coatings on the corrector plate, highly reflective index mirror coatings, and low-absorption/high-transmission glass components to ensure that the maximum amount of light is gathered and transmitted to the user's eye. This system ensures bright and clear high-contrast images with accurate color rendition across the entire visual spectrum without visible distortion at the edges. Celestron includes a standard 1.25" visual back to accept eyepieces and accessories such as the 40mm eyepiece and 90° diagonal supplied with the optical tube assembly (OTA). This OTA is offered here without a mount or tripod for users who already have a support system—just ensure the mount's payload capacity exceeds 27.5 pounds to safely carry the weight and that the mount has a Losmandy-style saddle to match the OTA's CGE mounting plate.
- 11" (279.4mm) aperture
- f/10 focal ratio
- 2800mm effective focal length
- Schmidt-Cassegrain design optical path
- StarBright XLT optical coatings
- Resolution: 0.5 arcsec (Rayleigh); 0.42 arcsec (Dawes)
- Secondary mirror obstruction: 3.75" (95 mm); 34% by diameter; 12% by area
- Maximizes light transmission through optical path
- Improves color rendition, contrast, sharpness, resolution, and brightness
- Broadband system provides flat wavelength transmission across the entire visual spectrum
- Multi-layer mirror coatings with layers of aluminum, SiO2 (quartz), and TiO2 (titanium dioxide)
- Multi-layer anti-reflective corrector plate coatings with layers of MgF2 (magnesium fluoride) and HfO2 (hafnium dioxide); hafnium has a wider band-pass than the commonly used titanium
- High-transmission water white glass corrector plate limits light loss due to internal absorption
- Optical tube only—mount and tripod required for proper use
- Supplied with CGE dovetail plate, which is compatible with Losmandy-style saddles
- Mount must have a payload capacity of over 27.5 pounds to safely support the OTA
- Visual back:
- Standard threads for Schmidt-Cassegrain telescope optical tubes
- 1.25" holder accepts 1.25" eyepieces and accessories
- Eyepiece:
- 1.25"-diameter barrel
- Accepts most 1.25" astronomical filters
- 40mm focal length produces 70x magnification
- Diagonal:
- 1.25"-diameter barrel
- 90° angle places head in comfortable viewing position when scope is aimed at or near the zenith
- Star diagonal corrects view horizontally, but not vertically
- Finderscope:
- 9x magnification
- 50mm aperture
- Mounting bracket included
Engineered to bridge the gap between their Advanced VX & heavy-duty CGX-L mounts, the Celestron CGEM II GoTo German Equatorial Mount delivers the performance required for capturing clear images during astrophotography sessions or resolving dim details when observing through an eyepiece. To make it compatible with a wide assortment of optical tube assemblies, Celestron outfitted the CGEM II with a dovetail saddle designed to accept the standard Vixen-style (Celestron's CG-5) and the larger Losmandy (Celestron CGE) dovetail bars.
Through the use of high-torque dual-axis low-cog DC servo motors, optical encoders on the motors, backlash compensation, and Permanent Periodic Error Correction (PPEC) the mount is capable of precise positioning and tracking accuracy to ensure your target object stays centered while constantly improving its performance the more you use it.
The brain of the system is the NexStar+ computer controller, which is equipped with a database of over 40,000 objects, including the planets, stars, nebulae, galaxies, and the complete Messier catalog; it can also be programmed with up 100 custom user-defined objects with filters to create custom object lists. Its intuitive menu-driven user interface makes observing the sky, day and night, fast and easy. Features such as guided tours, extended information on 200 popular objects, and multiple alignment options make the NexStar+ controller an invaluable tool to new users and experienced stargazers alike.
- 40-pound payload capacity
- Uninterrupted tracking below meridian to enable observation from a raised location such as a balcony or hilltop
- Internal cables eliminate snag hazards in the dark or when operating the mount remotely
- Counterweight bar with 17-pound counterweight allows you to properly balance your OTA with accessories and imaging systems
- Dual CG-5 (Vixen) and CGE (Losmandy) dovetail saddle make it compatible with most large and small OTAs on the market
- Dedicated autoguider port for making corrections when astroimaging
- Runs on the included 12V DC power cord
- Dual-axis low-cog DC servo motors
- High-torque motors for helping to smoothly drive heavier loads
- Dual motor encoders improve tracking and location accuracy with reduced vibrations
- Clutch levers for manual movement, levers are longer than normal to make tightening and loosening easier
- 40,000+ object database with filters for creating custom object lists
- 100 user-defined programmable celestial or terrestrial objects
- Enhanced information on over 200 objects
- Nine slew speeds: 4°/sec, 2°/sec, 1°/sec, 0.3°/sec, 32x, 16x, 8x, 4x, 2x
- Three tracking rates: Sidereal, Solar, Lunar
- Solar System alignment method allows to view the moon and planets during the day
- Built-in polar alignment program to polar align on any star in the sky
- Sky Tour Mode: System seeks out the best objects for the date and time and automatically slews to them
- Identify Mode: Use to identify an unknown object in the field of view, or to find other celestial objects that are close to where the user is viewing
- Anti-backlash compensation: Trains out the intrinsic play between gears for more precise slewing and tracking
- Permanent Periodic Error Correction (PPEC): System learns its internal tracking errors and improves over time for more precise tracking, requiring fewer corrections
- Built-in instructions guide you through the alignment procedures
- 4-line, 18-character LCD display with a 19-button fiber-optic backlit LED keypad
- RS-232 communication port on hand control to control the telescope via a personal computer
- Supports English, French, Italian, German, and Spanish
- Solar system: Seven planets, moon, sun, and Pluto
- Custom lists of all the brightest stars, double stars, variable stars, and asterisms
- Custom lists of galaxies, nebulae, and clusters, as well as the complete Messier catalog and select NGC objects
The Celestron CGEM II Tripod has 2" diameter steel legs with graduated markings that make it easy to extend the legs to the same height. It comes with a 17 lb counterweight.
Use the Celestron 17 lb Counterweight by itself or with other weights to balance your OTA and accessories on Celestron CG-5, CGEM, CG-4 mounts; or any similar mount with a 0.75" (19mm) center bore hole. A large thumbscrew allows you to lock the weight anywhere along the counterweight shaft to allow for precise balance.