Celestron Omni XLT AZ 102 Instruction Manual - Page 38

CCD Imaging for Deep Sky Objects Special cameras have been developed for taking images of deep sky images. These have evolved over the last several years to become much more economical and amateurs can take fantastic images. Several books have been written on how to get the best images possible. The technology continues to evolve with better and easier to use products on the market. Terrestrial Photography Your telescope makes an excellent telephoto lens for terrestrial (land) photography. Your telescope is in essence a long focal length telephoto lens. 35mm SLR cameras are mounted directly to the telescope (using the built-in TAdapter on the refractors and Newtonian or using the # 93633-A T-Adapter for the Schmidt-Cassegrain). For using a digital camera you will need the Universal Digital Camera Adapter (# 93626). You can take images of various scenic views, wildlife, nature, and just about anything. You will have to experiment with focusing, speeds, etc. to get the best image desired. Metering The Omni Series telescopes have fixed apertures and, as a result, fixed f/ratios. To properly expose your subjects photographically, you need to set your shutter speed accordingly. Most 35mm SLR cameras offer through-the-lens metering which lets you know if your picture is under or overexposed. Adjustments for proper exposures are made by changing the shutter speed. Consult your camera manual for specific information on metering and changing shutter speeds. Reducing Vibration Releasing the shutter manually can cause vibrations, producing blurred photos. To reduce vibration when tripping the shutter, use a cable release. A cable release keeps your hands clear of the camera and lens, thus eliminating the possibility of introducing vibration. Mechanical shutter releases can be used, though air-type releases are best. Blurry pictures can also result from shutter speeds that are too slow. To prevent this, use films that produce shutter speeds greater than 1/250 of a second when hand-holding the lens. If the lens is mounted on a tripod, the exposure length is virtually unlimited. 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. 38