Celestron CGEM 1100 HD Computerized Telescope EdgeHD Optics Manual - Page 13

Another way to reduce vibration is with the Vibration Suppression Pads (#93503). These pads rest between the ground and tripod feet. They reduce the vibration amplitude and vibration time. CCD Imaging Fastar Option - Using your EdgeHD telescope at f/2 with optional lens assembly The EdgeHD telescopes are equipped with a removable secondary mirror that allows you to convert your f/10 telescope into an f/2 imaging system capable of exposure times 25 times shorter than those needed with a f/10 system! The Fastar compatible telescope's versatility allows it to be used in many different f-number configurations for CCD imaging, making it the most versatile imaging system available today. With an optional lens assembly you can easily convert your Fastar compatible telescope to f/2 prime focus use in a matter of seconds. This makes the system ideal for imaging deep-sky objects as well as planetary detail. Described below is the configuration of each F-number and the type of object best suited to that kind of imaging. Secondary Mirror Secondary Mirror Retaining Ring Secondary Mirror Mount Handle Corrector Plate Figure 3-4 - The Fastar Compatible Optical System The above figure shows how the secondary mirror is removed when using the optional CCD camera for f/2imaging. Warning: The secondary mirror should never be removed unless installing the optional f/2 lens assembly. Adjustments to collimation can easily be made by turning the screws on the top of the secondary mirror mount without ever having to remove the secondary mirror (see Telescope Maintenance section of this manual). The F/# stands for the ratio between the focal length and the diameter of the light gathering element. For example, the EdgeHD 11" optical tube has a focal length of 110 inches and a diameter of 11 inches. This makes the system an f/10, (focal length divided by diameter). When the secondary is removed and the CCD camera is placed at the Fastar position, the system becomes f/2, this is a unique feature to some Celestron telescopes (see figures below). 13