INSTRUCTION MANUAL Orion 8" and 10" f/3.9 Newtonian Astrographs #8297 8" f/3.9, #8296 10" f/3.9 #8296 Providing Exceptional Consumer Optical Products Since 1975 OrionTelescopes.com Customer Support (800) 676-1343 • E-mail: support@telescope.com Corporate Offices (831) 763-7000 • 89 Hangar Way, Watsonville, CA 95076 © 2011 Orion Telescopes & Binoculars IN 406 Rev.
" Accessory collar Finder scope bracket 9x50 Finder Scope Tube rings Optical tube Focus wheel Drawtube tensioning thumbscrew Fine focus wheel 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.
1.25" Eyepiece holder Accessory lock thumbscrews 2" Accessory collar Eyepiece lock thumbscrews Drawtube tensioning thumbscrew 11:1 Fine focus wheel Coarse focus wheels Figure 2. The 2" dual-speed (11:1) Crayford focuser packaging to ensure the telescope stays intact during shipping. Take a moment to inspect the telescope and all of its parts. Before proceeding with the instructions, refer to Figure 1 to familiarize yourself with some of the features and com ponents of the telescope. 1.
Attaching the Finder Scope The included 9x50 crosshair finder scope (Figure 3a) is useful for locating objects in the sky and centering them in the 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 bracket until the screw ends are flush with the inside surface of the bracket.
Cooling the Telescope All optical instruments need time to reach “thermal equilibrium.” 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 telescope as cold as possible. If it has to adjust to more than a 40°F temperature change, allow at least one hour.
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 corrector 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.
Reflective surface of collimation cap Primary mirror center mark drawtube Reflection of primary mirror clip a. b. c. 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.
The Collimation Cap Your f/3.9 Newtonian Astrograph comes with a “quick collimation cap” (Figure 9). This is a simple cap that fits on the focuser drawtube like a dust cap, but has a tiny hole in the center 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 surface provides a distinct visual reference that is helpful in centering the primary and secondary mirror reflections.
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.
Figure 13. The tilt of the secondary mirror is adjusted with a Figure 14. The tilt of the primary mirror is adjusted by turning of the three alignment set screws by, say, one full turn, and then tighten the other two to take up the slack (Figure 13). Do not loosen the center screw during this process. The goal is to center the primary mirror reflection in the secondary mirror, as in Figure 8d. When it is centered, you’re done adjusting the secondary mirror.
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.
4. Specifications Orion 8" f/3.9 Newtonian Astrograph Optical configuration: Newtonian reflector Orion 10" f/3.9 Newtonian Astrograph Optical configuration: Newtonian reflector Aperture: 203mm Aperture: 254mm Focal length: 800mm Focal length: 1000mm Focal ratio: f/3.9 Focal ratio: f/3.
