User manual ORION TELESCOPES & BINOCULARS REV C 9024 AV 90EQ

[. . . ] INSTRUCTION MANUAL Orion® AstroViewTM 90mm EQ #9024 Equatorial Refracting Telescope Customer Support (800) 676-1343 E-mail: support@telescope. com Corporate Offices (831) 763-7000 Providing Exceptional Consumer Optical Products Since 1975 P. O. C 05/02 Piggyback camera adapter Tube mounting rings Finder scope bracket Tube ring mounting plate Dec. slow-motion control Counterweight lock knob Counterweight shaft Counterweight Latitude locking T-bolt Azimuth lock knob Latitude adjustment T-bolt Alignment screws (2) Eyepiece Star diagonal Focus knob Dec. setting circle Finder scope Accessory tray bracket attachment point Tripod leg lock knob Accessory tray bracket Accessory tray Figure 1. [. . . ] Insert the star diagonal into the focuser drawtube and an eyepiece into the star diagonal (secure with the thumbscrews). Point the telescope at a distant subject and center it in the field of view. Now, slowly rotate the focus knob until the object comes into sharp focus. Go a little bit beyond sharp focus until the image just starts to blur again, then reverse the rotation of the knob, just to make sure you hit the exact focus point. If you wear eyeglasses, you may be able to keep them on while you observe, if your eyepieces have enough "eye relief" to allow you to see the whole field of view. You can try this by looking through the eyepiece first with your glasses on and then with them off, and see if the glasses restrict the view to only a portion of the full field. If they do, you can easily observe with your glasses off by just refocusing the telescope the needed amount. Calculating the Magnification It is desirable to have a range of eyepieces of different focal lengths, to allow viewing over a range of magnifications. To calculate the magnification, or power, of a telescope, simply divide the focal length of the telescope by the focal length of the eyepiece (the number printed on the eyepiece): Telescope F. L. = Magnification For example, the AstroView 90 EQ, which has a focal length of 910mm, used in combination with the suppled 25mm Sirius Plössl eyepiece, yields a magnification of: 910 ÷ 25 = 36x Every telescope has a useful magnification limit of about 2x per millimenter of aperture. Using Your Telescope-- Astronomical Observing Choosing an Observing Site When selecting a location for observing, get as far away as possible from direct artificial light such as streetlights, porch lights, and automobile headlights. The glare from these lights will greatly impair your dark-adapted night vision. Set up on a grass or dirt surface, not asphalt, because asphalt radiates more heat. Heat disturbs the surrounding air and degrades the images seen through the telescope. Avoid viewing over rooftops and chimneys, as they often have warm air currents rising from them. Similarly, avoid observing from indoors through an open (or closed) window, because the temperature difference between the indoor and outdoor air will cause image blurring and distortion. If at all possible, escape the light-polluted city sky and head for darker country skies. You'll be amazed at how many more stars and deep-sky objects are visible in a dark sky!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 a halfhour 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° temperature change, allow at least one hour. [. . . ] Smudges on the tube can be wiped off with a soft cloth and a household cleaner such as Windex or Formula 409. Cleaning Lenses Any quality optical lens cleaning tissue and optical lens cleaning fluid specifically designed for multi-coated optics can be used to clean the AstroView's objective lens or the exposed lenses of your eyepieces or finder scope. Never use regular glass cleaner or cleaning fluid designed for eyeglasses. Before cleaning with fluid and tissue, blow any loose particles off the lens with a blower bulb or compressed air. [. . . ]