User manual ORION TELESCOPES & BINOCULARS 09990

[. . . ] INSTRUCTION MANUAL Orion SkyQuest XT10 Dobsonian Reflector ® TM #9990 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 Secondary mirror holder with 3-vane spider (not visible) Finder scope Finder scope bracket Eyepiece Focus knob Optical tube Altitude side bearing CorrecTension (XT) Friction Optimization system Right side panel Front brace Pull loop Eyepiece rack Handle Primary mirror cell Top baseplate Left side panel Ground baseplate Figure 1. The SkyQuest XT10 parts diagram. Foot (3) Welcome to an exciting new world of adventure!Your SkyQuest XT10 Dobsonian is a high-quality optical instrument designed to bring you dazzling views of the outer reaches of our universe. [. . . ] Adjusting the Primary Mirror The final adjustment is made to the primary mirror. It will need adjustment if, as in Figure 14d, the secondary mirror is centered under the focuser and the reflection of the primary mirror is centered in the secondary mirror, but the small reflection of the secondary mirror (with your eye inside) is off-center. The tilt of the primary mirror is adjusted with three springloaded collimation thumb screws on the back end of the optical tube (bottom of the primary mirror cell); these are the larger thumb screws. The other three smaller thumb screws lock the primary mirror's position in place; these thumb screws must be loosened before any collimation adjustments can be made to the primary mirror. To start, unthread the thumb screws that lock the primary mirror in place a few turns each (Figure 17). The thumb screws are slotted, so if they are too difficult to loosen with your fingers, use a flat-head screwdriver. Figure 15. To center the secondary mirror under the focuser, hold the secondary mirror holder in place with your fingers while adjusting the center screw with a Phillips screwdriver. Do not touch the mirror's surface! When the secondary mirror is centered in the focuser drawtube, rotate the secondary mirror holder slightly until the reflection of the primary mirror is as centered in the secondary mirror as it will get. It still may not be perfectly centered, but that is OK. Now tighten the three alignment screws to secure the secondary mirror in that position. This adjustment will rarely need to be done, if ever. If the entire primary mirror reflection is not visible in the secondary mirror, as in Figure 14c, you will need to adjust the tilt of the secondary mirror. This is done by alternately loosening one of the three alignment screws while tightening the other two, as depicted in Figure 16. The goal is to center the pri- Figure 17: The three thumb screws that lock the primary mirror in place must first be loosened before any adjustments can be made. Figure 18: The tilt of the primary mirror is adjusted by turning one or more of the three spring-loaded collimation thumb screws. Figure 16: Adjust the tilt of the secondary mirror by loosening or tightening the three alignment screws with a Phillips screwdriver. Now, try tightening or loosening one of the spring-loaded collimation thumb screws one turn (Figure 18). Look into the focuser and see if the secondary mirror reflection has moved closer to the center of the primary mirror reflection. Repeat this process on the other two collimation thumb screws, if 11 necessary. It will take a little trial and error to get a feel for how to tilt the mirror in this way to center the reflection. (It helps to have two people for primary mirror collimation, one to look in the focuser while the other adjusts the collimation thumb screws. ) Do not loosen (i. e. , rotate counter-clockwise) each collimation thumb screw too much, or the thumb screw will completely unthread from the mirror cell. Rather, try tightening the other two collimation thumb screws. Once the secondary mirror reflection is centered in the primary mirror reflection, retighten the thumb screws that lock the primary mirror's position in place. The view through the focuser should now resemble Figure 14a; the reflection of the primary mirror is centered in the secondary mirror, and the reflection of the secondary mirror is centered in the reflection of the primary mirror. A simple star test will tell you whether the optics are accurately collimated. [. . . ] This is done by removing the six screws that connect the entire mirror cell to the steel tube. These screws are located on the outside of the tube, just above the mirror cell casting. Now, remove the mirror from the mirror cell by first removing the four mirror clips that secure the mirror in its cell. Use a Phillips screwdriver to unthread the mirror clip anchor screws. [. . . ]