Celestron CGEM II 925 HD - 9.25" EdgeHD on CGEM II GoTo Equatorial Mount - 12018

Celestron   ——   SKU: CEL-12018
$4,653.62 CAD
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Product Info

CGEM II 925 HD combines Celestron's newly redesigned CGEM II computerized equatorial mount with its acclaimed EdgeHD optical system.  With over 9 inches of aperture and our premium StarBright XLT coatings, the CGEM II 925 HD gives you over 1000 times the light gathering power than the unaided eye.  Designed to give diffraction limited performance and offer more resolution than the 800 with less weight than the 1100, the CGEM II 925 HD is a premier astro-imaging telescope.


EdgeHD is an aplanatic, flat field Schmidt-Cassegrain telescope that produces aberration-free images across a wide visual and photographic field of view. The optical system was designed to reduce more than just off-axis star coma; it also provides an astrograph-quality flat focal plane all the way to the edge of the field of view. 

Many optical designs that advertise themselves as "astrographs" actually only produce pinpoint stars across a curved focal plane. While this may be acceptable for some visual observing, stars will appear out of focus at the edge when used with the flat chip sensor of a digital camera. EdgeHD optics produce a focal plane more than three-times flatter than a standard Schmidt-Cassegrain telescope and dramatically flatter than competing coma-free designs. This guarantees you visibly sharp stars across some of the largest CCD chips available today.

Superior edge performance not only creates rounder, more pleasing stars, but actually improves the resolution and limiting magnitude when compared to telescopes of equal aperture. With Celestron’s StarBright XLT optical coatings on every surface, EdgeHD optics gives you maximum light throughput across the widest visual and photographic spectrum.

In addition to EdgeHD’s optimized optical design, the telescope tube has been redesigned to make sure you get the most from your optics each and every night.

MIRROR CLUTCHES - Flexible tension clutches hold the mirror in place and reduce image shift when taking long exposure astro-images. Once focused, the flexible rods allow the mirror to be held in place without putting any force or pressure on the mirror assembly, keeping the image centered in the eyepiece (or on the sensor).

TUBE VENTS - Cooling vents located on the rear cell allow hot air to be released from behind the primary mirror. Each vent has an integrated 95-micron micromesh filter guaranteed to let warm air out without letting dust in.

FASTAR VERSATILITY - EdgeHD is the most versatile imaging telescope available today. At its native f/10, you can achieve the image scale necessary to capture the smallest of deep sky objects. Add the optional reducer lens—custom-designed for your size EdgeHD tube—and you can increase your field of view without sacrificing optical performance. A Barlow lens gives you added power for high-resolution planetary, lunar and solar imaging. All EdgeHD optical tubes are Fastar-compatible, allowing the secondary mirror to be removed and replaced with a third party lens accessory for ultra-fast f/2 wide field imaging.

Every EdgeHD that ships has been tested not only for the surface quality of each optical component, but also with a camera and artificial star to ensure the imaging system meets our rigid quality assurance.  This “final acceptance test” confirms the EdgeHD will perform in the field and deliver high-quality astroimages.


A fresh update to the venerable CGEM mount, the CGEM II has a fresh, attractive, bold appearance and is capable of carrying Celestron’s higher-end SCT optical tubes (up to 11") securely and vibration free, which is ideal for both imaging and visual observing. Capable of holding 40 lbs. of payload and slewing at 5° per second, you will be able to instantly point to any of the celestial objects in the database.


CGEM II was designed to be ergonomically friendly with large Altitude and Azimuth adjustment knobs for quick and easy polar alignment adjustment. The internal RA and DEC motor wiring provides a clean look and an easy and trouble free set up.


The CGEM II series features Celestron’s innovative Polar alignment procedure called All-Star™. All-Star allows users to choose any bright star, while the software calculates and assists with polar alignment. Another great feature of the CGEM II sure to please astroimagers, is the Permanent Periodic Error Correction (PEC) which will allow users to train out the worm gears periodic errors, while the mount retains the PEC recordings.


For objects near the Meridian (imaginary line passing from North to South), the CGEM II will track well past the Meridian for uninterrupted imaging through the most ideal part of the sky. The CGEM II mount has a robust database with over 40,000 objects, 100 user defined programmable objects and enhanced information on over 200 objects. Celestron's CGEM II mount is the perfect fit between the Advanced Series and CGE Series. Offering the portability of the Advanced Series and the precision of the CGE.



  • 9.25” EdgeHD optics
  • CGEM II computerized equatorial mount
  • Celestron’s premium StarBright XLT coatings provide maximum light transmission
  • A 9x50 finderscope, 2” mirror diagonal for more comfortable viewing, and wide-angle 23 mm Luminos 2" eyepiece are all included


  • EdgeHD aplanatic, flat field SCT optics for pinpoint stars to the edge of the largest imaging sensors and widest eyepieces.  Lightweight and portable
  • Aluminum optical tube with tube vents featuring an integrated 95-micron mesh filter allows hot air to be released from behind the primary mirror. Mirror support knobs hold the mirror in place and reduce image shift during imaging
  • Versatile design accommodates 3 focal ratios: native f/10, f/7 with the addition of a focal reducer, or ultra-fast f/2 imaging with a removable secondary mirror and third-party accessories


  • 40 lbs payload capacity
  • Dual-fit Vixen/CG-5 and Losmandy/CGE dovetail saddle
  • 2" steel legs with height index marks for quick leveling
  • USB 2.0 port on hand control for direct links to a PC via ASCOM supported software.
  • 40,000 object database with over 100 user-definable objects and expanded information on over 200 objects
  • Internal cabling throughout for worry-free remote operation
  • Low cog DC Servo motor with integrated optical encoders offer smooth, quiet operation
  • Able to track past the meridian allowing seamless imaging
  • Permanent periodic error corrections allow users to train out the worm gears periodic errors once, while the mount retains the PEC recordings.
  • Software Features include: Mount Calibration, Database Filter Limits, Hibernate, five Alignment Procedures, and user-defined slew limits
  • Built-in polar alignment program to polar align on any star in the sky
  • Longer clutch levers to make tightening and loosening of clutches easier
  • Custom database lists of all the most famous deep-sky objects by name and catalog number
  • Solar System alignment method allows to view the moon and planets during the day
  • Permanent Programmable Periodic Error Correction (PEC) corrects periodic tracking errors inherent to all worm drives
  • Custom Rate 9 feature allows to set maximum slew rate
  • Tandem mode allows to star align the mount even when positioned for tandem scope use
  • RS-232 communication port on hand control to control the telescope via a personal computer
  • Includes NexRemote telescope control software, for advanced control of telescope via computer
  • Precision machined 40 mm diameter steel Polar shafts supported by multiple tapered roller bearings and ball bearings
  • GPS-compatible with optional SkySync GPS Accessory


Optical Tube Info
Optical Design EdgeHD
Aperture (mm) 234.95 mm (9.25 in)
Focal Length 2350 mm (93 in)
Focal Ratio 10
Focal Length of Eyepiece 1 (mm) 23 mm (0.91 in)
Magnification of Eyepiece 1 102 x
Finderscpoe 9x50
Star Diagonal 2" w/ 1.25" adapter
Optical Tube Aluminum
Highest Useful Magnification 555 x
Lowest Useful Magnification 34 x
Limiting Stellar Magnitude 14.4
Resolution (Rayleigh) 0.59 arc seconds
Resolution (Dawes) 0.49 arc seconds
Light Gathering Power (Compared to human eye) 1127 x
Secondary Mirror Obstruction 3.35 in (85 mm)
Secondary Mirror Obstruction by Diameter 36%
Secondary Mirror Obstruction by Area 13%
Optical Coatings StarBright XLT
Optical Tube Length 22 in (559 mm)
Optical Tube Weight 21 lbs. (9.53 kg)
Dovetail Compatibility CGE Mount
Mount Info
Mount Type German Equatorial Mount
Tripod 2” Steel tripod with graduated markings on lower section
Dovetail Mount Directly connects to both CG-5 & CGE dovetail bars
Payload Capacity 40 lbs
Latitude Range 15º – 70º
Power Requirements 12 VDC, 3.2 amps
Ports 1x Hand control port, 1x Auxiliary Port, 1x Auto guider port, 1 USB 2.0 port (on hand control)
Motor Drive Low cog DC servo motors
Slew Speeds 9 slew speeds
Tracking Rates Sidereal, Solar and Lunar
Tracking Modes EQ North and EQ South
Alignment Procedures AutoAlign, 2-Star Align, Quick Align, 1-Star Align, Last Alignment, Solar System Align
Computerized Hand Control Double line, 16 character Liquid Crystal Display; 19 fiber optic backlit LED buttons, USB 2.0 port for PC connection
Database 40,000+ objects, 100 user defined programmable objects. Enhanced information on over 200 objects
Mount Weight 40 lbs
Tripod Weight 20 lbs
Weight of Counterweight 1 x 17 lbs, 1 x 11 lbs counterweights
Total Weight of Mount Kit 77 lbs