The CGE Pro 925 HD combines Celestron's state of the art CGE Pro Computerized Equatorial mount with its new EdgeHD optical system. With over 9 inches of aperture and our premium StarBright XLT coatings, the CGE Pro 925 HD gives you over 1000 times the light gathering power than the unaided eye.
New Optical Design
The EdgeHD optical system takes all of the compact power popularized by the Schmidt Cassegrain Telescope (SCT) and combines it with an improved high definition optical system for wide field, astrograph quality images.
As a visual instrument, EdgeHD optics deliver pinpoint images even with your widest field eyepiece. You can search for all of the Messier Catalog objects, and see hundreds of other equally interesting NGC, IC and Caldwell objects with amazing clarity. For astroimaging, the EdgeHD optics produce aberration-free images across your favorite CCD or DSLR camera. All EdgeHD optics are designed to produce an extremely flat focal plane precise enough to match the strict tolerances of the largest commercial CCD detectors, allowing all stars to be in tight focus to the very edge of the chip.EdgeHD Whitepaper
The Celestron Product Development team has released a whitepaper outlining the technology behind EdgeHD. This paper describes the development goals, design decisions, optical performance, and their practical realization in 8-, 9.25-, 11-, and 14-inch apertures. We include cross-sections of the EdgeHD series, comparative spot diagrams for the EdgeHD and competing “coma-free” Schmidt-Cassegrain designs, a table with specifications for visual and imaging, graphics showing how to place sensors at the optimum back-focus distance, and details on the construction and testing of the EdgeHD telescope series.
Click here to download the whitepaper.
Some companies boast that their telescopes give diffraction limited stars in the very center of the field of view. EdgeHD optics not only produce diffraction limited stars on axis, but maintain diffraction limited stars across the entire field of view of many of the most popular astrophotography cameras. Even at the very edge of a full frame camera chip, the EdgeHD 9.25 delivers diffraction limited stars of only 1 arc seconds.
The EdgeHD 9.25" optics produces a focal plane almost 9 times flatter than the standard equivalent SCT telescope with diffraction limited stars across the entire SBIG STL11000 field of view!
Along with the newly designed optics, the EdgeHD also has re-designed mechanics guaranteed to help you get the maximum performance from your instrument.
Mirror Locks – To hold the mirror in place and reduce image shift during imaging.
Tube Vents - Each vent has an integrated 60 micron micro-mesh filter allowing hot air to be released from behind the primary mirror.
Fastar Versatility – All EdgeHD optical tubes are equipped with a removable secondary mirror for fast f/2 CCD imaging. Not only does imaging in the FASTAR configuration allow for exposure times that are 25 times faster than at f/10, but also yields a field of view five times wider. A perfect combination for imaging your favorite wide field objects in a fraction of the time. (FASTAR imaging requires a third party lens assembly in place of the secondary mirror).
Axiom Eyepiece - EdgeHD 9.25" optical tubes come with Celestron's top of the line Axiom eyepiece. With a 23 mm focal length and 82° AFOV, you get an incredible combination of power and wide field of view. Plus each Axiom eyepiece is optimized to deliver pinpoint images when used with a flat field telescope.
Learn more about the benefits and features of this new optical system by going to the EdgeHD web page.
CGE PRO Mount
In addition to being fully computerized with a database of over 40,000 celestial objects, the CGE Pro German Equatorial mount has been completely redesigned to offer numerous design advantages:
- Increased Payload Capacity - With a maximum payload of 90 lbs, the CGE Pro mount is able to hold the 9.25" telescope more securely even when fully loaded with all your imaging gear.
- All-Star Polar Alignment - Choose any bright alignment star for a software assisted alignment of the mount's polar axis that will have you ready for imaging even if you can't see the North Star.
- No-Tool Polar Alignment - Larger hand knobs for both Altitude and Azimuth adjustments.
- Meridian Tracking - Extended tracking past the Meridian of up to 20 degrees of uninterrupted imaging through the best part of the sky.
- Faster Slew Speed - Improved gearing and motors provide faster slew speeds than ever before with a maximum slew rate of over 5°/per second.
- Accuracy - The hallmark of any telescope mount is its ability to find, center and track celestial objects with the highest degree of accuracy.
- Pointing - With just a standard hand control alignment, CGE Pro has the ability to center a star in your eyepiece or CCD chip to within 5 arc minutes. Using NexStar's advanced pointing features such as Calibration Stars, Sync and Precise GoTo, further improves the pointing accuracy to as low as 1 arc minute in the desired region of the sky.
- Tracking - With larger .75" pitch diameter worm, precision made cut-steel gears in gearboxes, and seven slot skewed armature motors, the CGE Pro delivers smooth +/- 5 arc second tracking accuracy typical unguided periodic error, which can be further reduced with PPEC
- Mount Calibration - Celestron's NexStar hand control has built-in compensation features essential for accurately placing small objects on the center of your CCD chip or high power eyepiece. Aligning on multiple Calibration Stars creates a model of the opto-mechanical inaccuracies inherent in all equatorial mounts. This model is stored within the hand control and is used to compensate for these inaccuracies, thus improving your pointing precision each time you slew your telescope.
CGE PRO Tracking Data
The following graphs display R.A. worm gear tracking accuracy of the CGE Pro Equatorial mount in 4 conditions: Figure 1 – Raw unguided tracking that isolates the periodic error; Figure 2 – Tracking with Permanent Periodic Error Correction (PPEC) enabled; Figure 3 – Guided tracking with an autoguider; and Figure 4 – Guided tracking with an autoguider and PPEC enabled. Data was acquired from Celestron’s engineering team using an EdgeHD 800 optical tube and NexImage camera at f/10. This data represents the typical performance of a CGE Pro under average seeing conditions from urban skies in Torrance, CA. Figure 2 has a cubic fit applied to the graph, and Figures 1, 3 and 4 have linear drift removed (to better show repeatable error). All Figures show 22 minutes of tracking, which covers 4 full rotations of the CGE Pro R.A. worm gear.
Figure 1. This graph displays the R.A. worm gear tracking accuracy for a typical CGE Pro equatorial mount. The graph shows 4 periods of the worm gear which yields about +/-7 arc seconds of periodic error. The minimal periodic error is both very predictable and gradual, allowing short unguided images to be taken, or much longer exposures with extremely accurate tracking when used with an autoguider.
For more information about Celestron's new mount, go to the CGE Pro mount web page.