User manual SKY-WATCHER COLLAPSIBLE DOBSONIANS

[. . . ] Mounting Plate 13 12 11 10 SLOW GUIDE 1 2 3 4 5 NM L 2 FAST 1 3 9 5 4 7 6 6 7 SET GO 8 E REFLECTOR FG HI HEQ5 J D K L C BA 16 15 E FG 14 13 12 11 10 9 SLOW GUIDE COLLAPSIBLE DOBSONIANS 1 2 3 4 5 D C H I J K L A 2 FAST 1 3 5 4 7 6 B 6 7 16 15 14 SET GO HEQ5 A. Eyepiece Focus Tube Focus Knob Dust Cap/Mask (Remove before viewing) Finderscope Finderscope Bracket Alignment Screw Tension Adjustment Screw Piggyback Bracket Tube Rings Telescope Main Body Primary Mirror Location A. L. COLLAPSIBLE DOBSONIANS Eyepiece Focus Tube Focus Knob Dust Cap/Mask (Remove before viewing) Finderscope Finderscope Bracket Alignment Screw Tension Adjustment Screw Piggyback Bracket Tube Rings Telescope Main Body Primary Mirror Location 8 13 12 11 10 SLOW GUIDE 1 2 3 4 5 2 FAST 1 3 9 5 4 7 6 SET GO 6 7 1. Mounting Plate 8 TABLE OF CONTENTS ASSEMBLING YOUR TELESCOPE Tripod Set Up Mount Assembly Telescope Assembly Finderscope Assembly Eyepiece Assembly Hand Control Holder Installation (For SynScan Only) TM 5 5 5 6 6 7 7 8 8 8 9 10 10 10 14 17 18 19 19 21 21 I II IV V OPERATING YOUR TELESCOPE Aligning the Finderscope Balancing the Telescope Operating the Mount Manually Using the Optional Barlow Lens Focusing Polar Alignment Pointing Your Telescope Choosing the Appropriate Eyepiece OBSERVING THE SKY PROPER CARE FOR YOUR TELESCOPE Collimating a Newtonian Reflector Collimating a Refractor with the Adjustable Objective-Lens Cell Cleaning Your Telescope APPENDIX A - STANDARD TIME ZONES OF THE WORLD APPENDIX B - OPTIONAL ACCESSORIES APPENDIX C - RECOMMENDED READING APPENDIX D - GLOSSARY NEVER USE YOUR TELESCOPE TO LOOK DIRECTLY AT THE SUN. [. . . ] Pointing toward the western or eastern horizon Now, consider pointing the telescope to the western (Fig. i-2a) or eastern (Fig. i-2b) horizon. If the counterweight is pointing North, the telescope can be swivelled from one horizon to the other around the Dec axis in an arc that passes through the NCP (any Dec arc will pass through the NCP if the mount is polar-aligned). It can be seen then that if the optical tube needs to be pointed at an object north or south of this arc, it has to be also rotated around the R. A axis. Fig. i-1 a. c. Celestial Pole + Fig. i-2 a. b. Telescope pointing East Counterweight pointing North (These diagrams applicable to HEQ5 and COLLAPSIBLE DOBSONIANS mounts) Rotation of the R. A. axis Telescope pointing West Counterweight pointing North 15 Telescopes with long focal lengths often have a "blind spot" when pointing near the zenith, because the eyepiece-end of the optical tube bumps into the mount's legs (Fig. i-3a). To adapt for this, the optical tube can be very carefully slipped up inside the tube rings (Fig. i-3b). This can be done safely because the tube is pointing almost vertically, and therefore moving it does not cause a Dec-balance problem. It is very important to move the tube back to the Dec-balanced position before observing other sky areas. Something which can be a problem is that the optical tube often rotates so that the eyepiece, finderscope and the focussing knobs are in less convenient positions. However, to adjust the positions of the finderscope and focussing knobs, loosen the tube rings holding the optical tube and gently rotate it. Do this when you are going to view an area for while, but it is inconvenient to do every time you briefly go to a new area. Finally, there are a few things to consider to ensure that you are comfortable during the viewing session. To determine an exit pupil, you divide the diameter of the primary of your telescope (in mm) by the magnification. Diameter of Primary mirror in mm Exit Pupil = Magnification For example, a 200mm f/5 telescope with a 40mm eyepiece produces a magnification of 25x and an exit pupil of 8mm. This combination can probably be used by a young person but would not be of much value to a senior. The same telescope used with a 32mm eyepiece gives a magnification of about 31x and an exit pupil of 6. 4mm which should be fine for most dark adapted eyes. In contrast, a 200mm f/10 telescope with the 40mm eyepiece gives a magnification of 50x and an exit pupil of 4mm, which is fine for everyone. 17 OBSERVING THE SKY Sky conditions Sky conditions are usually defined by two atmospheric characteristics, seeing, or the steadiness of the air, and transparency, light scattering due to the amount of water vapour and particulate material in the air. When you observe the Moon and the planets, and they appear as though water is running over them, you probably have bad "seeing" because you are observing through turbulent air. In conditions of good "seeing", the stars appear steady, without twinkling, when you look at them with unassisted eyes (without a telescope). Ideal "transparency" is when the sky is inky black and the air is unpolluted. Selecting an observing site Travel to the best site that is reasonably accessible. It should be away from city lights, and upwind from any source of air pollution. Always choose as high an elevation as possible; this will get you above some of the lights and pollution and will ensure that you aren't in any ground fog. Sometimes low fog banks help to block light pollution if you get above them. [. . . ] To find the True Field of View (also known as the Actual Field of View), divide the Apparent Field of View by the Magnification. Finderscope A low power telescope attached parallel to the main instrument which provides easy object locating and telescope aiming. Focal Length The distance of the light path from the objective (primary lens or mirror) to the convergence of the beam. Focal Ratio This is found by dividing an optical system's Focal Length by its Aperture. [. . . ]