Tele-Extender #5125 Standard Tele-Extender #5127 Variable Tele-Extender Your Orion Tele-Extender will allow you to take highmagnification photographs of celestial objects with a Schmidt-Cassegrain telescope. It is particularly useful for planetary astrophotography, close-ups of lunar craters, and extremely long distance terrestrial photography. when using a tele-extender. The eyepiece enlarges the image and therefore reduces the amount of light. Shorter-focal-length eyepieces magnify the image more, causing it to be dimmer. Dimmer images mean longer exposure times will be necessary. Tele-Extender Effective Focal Length Chart Below is a chart of effective focal lengths and f/ratios to assist you in determining the best combinations for your system. Values are rounded to the nearest 5 or 0 for convenience. For the variable tele-extender, the effective focal length below applies when the unit is fully extended. Shortening the variable tele-extender will reduce the effective focal length. Instrument 8" f/10 Base Focal Length2000mm Eyepiece 40mm 30mm 25mm 20mm 18mm 15mm 13mm 12mm 10mm 9mm 7mm 7000mm f/35 9500mm f/50 12000mm f/60 14000mm f/70 18000mm f/90 19000mm f/95 *22000mm f/115 *28500mm f/140 *29000mm f/140 *39000mm f/190 *41000mm f/210 8700mm f/35 1200mm f/50 14000mm f/60 17800mm f/70 12000mm f/90 24000mm f/95 28000mm f/110 *30000mm f/140 *36000mm f/145 *40300mm f/165 *52000mm f/210 9800mm f/35 13100mm f/50 15700mm f/60 19600mm f/70 21777mm f/80 26500mm f/100 30600mm f/115 *33000mm f/125 *40600mm f/150 *45000mm f/165 *58000mm f/215 10" f/10 2500mm 11"f/10 2800mm A. B. How To Use The Orion Tele-Extender The Standard Tele-Extender (A) is a fixed-length extension tube, which produces a fixed magnification for a given eyepiece used with the tele-extender. The Variable Tele-Extender (B) has an adjustable-length extension tube, allowing magnification to be changed without switching eyepieces. For high-powered photography through your SchmidtCassegrain, attach the visual back in the normal manner. Instead of inserting the star diagonal into the visual back, insert an eyepiece and hand tighten the set screw. Thread the tele-extender onto the visual back, over the eyepiece. Thread your T-ring onto the end of the tele-extender and attach your camera. Some telescopes do not have a separate visual back, such as the Meade LX5 series, LX6, and the Meade 2045. You may have to purchase a visual back to use a tele-extender. A 1.25" visual back which fits Meade and Celestron Schmidt-Cassegrain 4", 8", 10", 11", and 14" scopes is available from Orion (#15048). (Celestron C-90s and some other small spotting scopes have threads that will fit a tele-extender directly but require the use of .965" eyepieces to create the higher magnifications.) Most standard eyepieces are useable with a tele-extender. Some eyepieces have barrel assemblies that are too large to fit inside a tele-extender. See the diagram below for reference on how to attach a tele-extender to your telescope. When you look through your camera and focus the telescope, you will notice a dim, highly magnified image. This is normal *Beyond useful magnification--not recommended Focusing It can be quite difficult to focus the telescope, especially when using eyepiece projection! In fact, with most cameras the image in the viewfinder can be so dim that it may be difficult to find the focal point at all. Use a bright object such as the Moon or a bright star for focusing. Find and center this object in the telescope's field before installing the camera adapter. If your camera has interchangeable focusing screens, use a fine-ground glass screen. It will be much brighter and will make focusing easier. Vibration During Exposure It is very important to minimize vibration during an exposure. If your camera is equipped with a "mirror lock-up," use it before you start the photo. Use a cable release to trip the self-timer on the camera. To further reduce vibration, the best solution is the "hat trick." Set your camera's exposer time (shutter speed) to the "B" (bulb) setting, which will hold the shutter open indefinitely when triggered. Hold a black piece of cardboard or a "hat" in front of the telescope (but not touching it) while you open the shutter. Wait approximately 8 seconds and then remove the "hat." It is important that nothing touch the telescope or camera during the exposure. When you're finished exposing, place the "hat" in front of the telescope again and trip the cable-release to close the shutter. Camera T-Ring Tele-Extender (variable) Eyepiece Visual Back Schmidt-Cassegrain Customer Support (800) 676-1343 E-mail: support@telescope.com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P.O. Box 1815, Santa Cruz, CA 95061 IN 011 Rev. B Precautions Be very careful not to release the set screw holding the eyepiece before removing your camera and tele-extender. If the screw is released and the eyepiece falls through the extender tube, it can damage your camera. Customer Support (800) 676-1343 E-mail: support@telescope.com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P.O. Box 1815, Santa Cruz, CA 95061 ...