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INSTRUCTION MANUAL
Orion 8" and 10" f/3.9
Newtonian Astrographs
#8297 8" f/3.9, #8296 10" f/3.9
#8296
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© 2011 Orion Telescopes & Binoculars
IN 406 Rev. A 07/11
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2" Finder scope Accessory bracket collar 9x50 Finder Scope Optical tube Tube rings Focus wheel Drawtube Fine focus wheel tensioning thumbscrew Focus wheel Figure 1. The Orion 8" f/3.9 Newtonian Astrograph Congratulations on your purchase of an Orion f/3.9 Newtonian Astrograph! These powerful imaging telescopes feature “fast,” high-quality parabolic optics, a 2" dual-speed Crayford focuser, and excellent mechanical construction with some special features. Optimized for astrophotography wi
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then retighten the clamps. Rotating the telescope to achieve 1.25" Eyepiece holder Accessory lock a comfortable eyepiece or camera angle is done in the same thumbscrews fashion. Simply loosen the tube ring clamps just enough to allow the optical tube to rotate within the tube rings. Retighten 2" the tube ring clamps securely once you have reached the Accessory desired eyepiece or camera orientation. collar 2" Dual-Speed Crayford Focuser The f/3.9 Newtonian Astrograph features an all-meta
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Attaching the Finder Scope O-ring Finder Finder Nylon alignment The included 9x50 crosshair finder scope (Figure 3a) is use- (not visible) scope scope thumbscrew (2) ful for locating objects in the sky and centering them in the bracket main telescope’s field of view. To install it, first remove the O-ring from the bracket and place it over the body of the finder scope until it seats in the narrow groove near the middle of the finder. Unthread the two black nylon alignment screws on the b
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Cooling the Telescope All optical instruments need time to reach “thermal equilibri- um.” The bigger the instrument and the larger the temperature change, the more time is needed. Allow at least 30 minutes for your telescope to cool to the temperature outdoors. In very cold climates (below freezing), it is essential to store the tele- scope as cold as possible. If it has to adjust to more than a 40°F temperature change, allow at least one hour. You can use the telescope while it’s cooling d
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Attaching a CCD Camera The Orion f/3.9 Newtonian Astrographs are equipped to accept CCD cameras with a 2" nosepiece, or a 2" coma cor- rector in place of the nosepiece, which slides directly into the telescope’s focuser like an eyepiece (Figure 5). The 2" nosepiece is secured with the two thumbscrew locks. If your CCD imager does not include a compatible 2" nosepiece, or if you wish to utilize the camera’s T-threads without a coma cor- rector, a zero-profile prime focus camera adapter is re
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Reflective surface Primary mirror of collimation center mark cap drawtube Reflection of primary mirror clip b. c. a. d. e. Figure 8. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (b) With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (c) Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primar
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The Collimation Cap Your f/3.9 Newtonian Astrograph comes with a “quick collima- tion cap” (Figure 9). This is a simple cap that fits on the fo- cuser drawtube like a dust cap, but has a tiny hole in the cen- ter and a reflective inner surface. The collimation cap helps center your eye over the focuser drawtube so that aligning the optical components is easier to achieve. The reflective sur- face provides a distinct visual reference that is helpful in cen- tering the primary and secondary mirr
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one hand while turning the center screw with a large Phillips head screwdriver with your other hand (Figure 11). Turning the screw clockwise will move the secondary mirror toward the front opening of the optical tube, while turning the screw counter-clockwise will move the secondary mirror toward the primary mirror. When the secondary mirror is centered axially in the focuser drawtube, rotate the secondary mirror holder until the reflection of the primary mirror is as centered in the sec
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Figure 13. The tilt of the secondary mirror is adjusted with a Figure 14. The tilt of the primary mirror is adjusted by turning 2mm Allen wrench on the three setscrews surrounding the center one or more of the three large, spring-loaded collimation knobs. The Phillips-head bolt. three thinner thumbscrews lock the primary mirror in place. of the three alignment set screws by, say, one full turn, and knobs. It will take some trial-and-error using all three collima- then tighten the other two to
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Out of collimation Collimated Figure 15. A star test will determine if the telescope’s optics are properly collimated. A defocused view of a bright star through the eyepiece should appear as illustrated on the right if the optics are perfectly collimated. If the circle is unsymmetrical, as illustrated on the left, the optics need alignment. cap on the eyepiece opening. Keep the telescope inside the hard storage carrying case when not in use. Store it indoors or in a dry garage. Do not leav
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4. Specifications Orion 8" f/3.9 Newtonian Astrograph Orion 10" f/3.9 Newtonian Astrograph Optical configuration: Newtonian reflector Optical configuration: Newtonian reflector Aperture: 203mm Aperture: 254mm Focal length: 800mm Focal length: 1000mm Focal ratio: f/3.9 Focal ratio: f/3.9 Primary mirror: Low thermal expansion optical glass, Primary mirror: Low thermal expansion optical glass, parabolic figure parabolic figure Mirror coatings: Enhanced aluminum (94% Mirror coatings: Enhanced alumi
