What is the advantage of the CGEM II 800 EdgeHD's flat-field optics over a standard SCT?
The primary advantage of the EdgeHD design is its flat focal plane. A standard Schmidt-Cassegrain Telescope (SCT) has a curved field, causing stars at the edge of an image to appear slightly out of focus. The EdgeHD corrects for this field curvature and coma, delivering sharp, pinpoint stars across its 42mm image circle.
Is the 40 lb capacity of the CGEM II mount sufficient for the 800 EdgeHD with imaging gear?
The 8" EdgeHD tube weighs 14 lbs against the CGEM II's 40 lb capacity, and the mount carries SCT tubes up to 11" securely and vibration free.
How does the CGEM II 800 EdgeHD's Fastar compatibility enable f/2 imaging?
The secondary mirror is removable, so a third-party lens accessory, sold separately, can take its place for ultra-fast f/2 wide-field imaging.
How much detail can the CGEM II 800 EdgeHD resolve on Saturn in an f/10 configuration?
Every EdgeHD should resolve double stars to the Dawes limit (0.57 arc seconds here), show subtle shadings in Jupiter's belts and reveal the Cassini Division in Saturn's rings on a night of good seeing. The included 40mm eyepiece gives 51x, so you will want a higher-power eyepiece or a Barlow for planets.
Can I polar align the CGEM II 800 EdgeHD if my view of Polaris is blocked?
Yes. The CGEM II mount features Celestron's All-Star Polar Alignment procedure. This innovative software routine allows you to use any bright star in the sky to achieve an accurate polar alignment. After aligning on stars, the mount slews to where a bright star would be if accurately polar aligned, and you center it with the mount's altitude and azimuth adjustments, not the hand control.
What does Permanent Periodic Error Correction (PPEC) do for the CGEM II 800 EdgeHD?
PPEC lets you train out the worm gears' periodic errors once; the mount keeps the recording and corrects its tracking from then on.
How do I power the CGEM II 800 EdgeHD in the field?
The mount needs 12V DC, 3.2 amps. The included DC power cable plugs into a car's cigarette lighter outlet or a portable power supply, and a 12V AC adapter can also be used.
What is the correct back focus for imaging with the CGEM II 800 EdgeHD?
The optimal back focus for the 8-inch EdgeHD is 133.35 mm (5.25"). This is the distance measured from the threads on the rear cell of the telescope to your camera's sensor. Using the correct spacing is critical to achieving the flat-field, coma-free performance the EdgeHD optics are designed for. Celestron's T-adapter for the 8" places a camera at that distance.
Can I control the CGEM II 800 EdgeHD with a computer?
Yes. The NexStar+ hand control has a USB 2.0 port that allows you to connect to a PC for control via the included Celestron Starry Night Special Edition software or other astronomy programs.
Is the CGEM II 800 EdgeHD difficult to transport and set up?
The total kit weight is 92 lbs, but it breaks down into manageable components. The heaviest parts are the mount head (40 lbs), the tripod (20 lbs), and the optical tube (14 lbs). The CGEM II 800 HD is the lightest and most portable telescope in its class.
