User manual ORION TELESCOPES & BINOCULARS SKYQUEST AD B

[. . . ] NOTE: This addendum is for #9980 SkyQuest XT8 Dobsonian Telescopes shipped after 3/15/00 Addendum to the Instructions: Primary Mirror Adjustment #9980 SkyQuest XT8 Dobsonian Reflector Telescope There has been an improvement to your SkyQuest XT8 that is not mentioned in the provided instruction manual. [. . . ] 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 19). The thumb screws are slotted, so if they are too difficult to loosen with your fingers, use a flat-head screwdriver. Now, try tightening or loosening one of the spring-loaded collimation thumb screws one turn (Figure 20). 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 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 casting. [. . . ] The tilt of the primary mirror is adjusted by turning one or more of the three spring-loaded collimation thumb screws. Customer Support (800) 676-1343 E-mail: support@telescope. com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P. O. [. . . ]