CGEM Series Manual - Celestron

Another way to reduce vibration is with the Vibration Suppression Pads (#93503). These pads rest between the ground andtripod feet. They reduce the vibration amplitude and vibration time.CCD ImagingSCT telescope's versatility allows it to be used in many different f-number configurations for CCD imaging. It can be usedat f/6.3 (with the optional Reducer/Corrector), f/10, and f/20 (with the optional 2x Barlow) making it the most versatileimaging system available today. This makes the system ideal for imaging deep-sky objects as well as planetary detail.The key factors for good CCD imaging are; exposure time, field-of-view, image size, and pixel resolution. As the F/# goesdown (or gets faster), the exposure times needed decreases, the field-of-view-increases, but the image scale of the object getssmaller. What is the difference between f/6.3 and f/10? F/6.3 has about 2/3 the focal length of f/10. That makes the exposuretime needed about 2.5 times shorter than at f/10, the field of view 50% larger compared to that of f/10. (see Table below)FocalLength &SpeedTelescopeModelStandardCassegrain f/10WithReducer/Correctorf/6.3C8 80" (2032mm) 50.4" (1280mm)C9.25 93" (2350mm) 58" (1481mm)C11 110" (2800mm) 69" (1764mm)Table 7-3Auto GuidingThe CGEM mount has a designated auto guiding port for use with a CCD autoguider. The diagram below may be usefulwhen connecting the CCD camera cable to the telescope and calibrating the autoguider. Note that the four outputs are activelow,with internal pull-ups and are capable of sinking 25 mA DC.49