INSTRUCTION MANUAL Orion AstroView 120 EQ ® ™ #9026 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. Box 1815, Santa Cruz, CA 95061 IN 124 Rev.
Tube rings Objective lens cell Dew cap/ lens shade Right Ascension slow-motion control (not visible) Declination lock lever Latitude adjustment T-bolts Finder scope Finder bracket Counterweight shaft Small counterweight Large counterweight Eyepiece Star diagonal Focus knob Declination slow-motion control Counterweight lock thumbscrews “Toe saver” retaining bolt Right Ascension lock lever Polar axis finder scope Azimuth fine adjustment knobs Tripod leg Accessory tray bracket attachment point Accessor
Congratulations on your purchase of a quality Orion telescope! Your new AstroView 120 EQ Refractor is designed for high-resolution viewing of astronomical objects. With its precision optics and equatorial mount, you’ll be able to locate and enjoy hundreds of fascinating celestial denizens, including the planets, Moon, and a variety of deep-sky galaxies, nebulas, and star clusters. If you have never owned a telescope, we are pleased to welcome you to amateur astronomy.
2. Assembly Carefully open all of the boxes in the shipping container. Make sure all the parts listed in Section 1 are present. Save the boxes and packaging material. In the unlikely event that you need to return the telescope, you must use the original packaging. Assembling the telescope for the first time should take about 30 minutes. No tools are needed, other than the ones provided.
12.To place the finder scope in the finder scope bracket, first unthread the two black nylon screws until the screw ends are flush with the inside diameter of the bracket. Place the O-ring that comes on the base of the bracket over the body of the finder scope until it seats into the slot on the middle of the finder scope.
a. b. c. d. Figure 5. Proper operation of the equatorial mount requires that the telescope tube be balanced on both the R.A. and Dec. axes. (a) With the R.A. lock lever released, slide the counterweights along the counterweight shaft until they just counterbalance the tube. (b) When you let go with both hands, the tube should not drift up or down. (c) With the Dec. lock lever released, loosen the tube ring lock clamps a few turns and slide the telescope forward or back in the tube rings.
When the target object is centered on the crosshairs of the finder scope and in the telescope’s eyepiece, the finder scope is now aligned and ready to be used for an observing session. The finder scope and bracket can be removed from the dovetail for storage, and then reinstalled without significantly changing the finder scope’s alignment. The finder scope alignment should be checked before every observing session. This can easily be done at night, before viewing through the telescope.
Note: From this point on in your observing session, you should not make any further adjustments to the latitude of the mount, nor should you move the tripod. Doing so will undo the polar alignment. The telescope should be moved only about its R.A. and Dec. axes. Little Dipper (in Ursa Minor) Big Dipper (in Ursa Major) N.C.P. Polaris ter Poin a t S rs Cassiopeia Figure 8. To find Polaris in the night sky, look north and find the Big Dipper.
2. Rotate the date circle until the “0” line on the meridian offset scale lines up with the time meridian indicator mark. The meridian offset scale is printed on the inner circumference of the date circle, and is labeled “E20” to “W20”. The time meridian indicator mark is an engraved line on the exterior of the polar finder’s housing. It is on the “ring” of the housing that is closest to the date circle. 3. The R.A. setting circle is labeled in hours, from “0” to “23” (military time).
Remember, accurate polar alignment is not needed for casual visual observing. Most of the time, approximate polar alignment, as outlined previously, will suffice. Tracking Celestial Objects When you observe a celestial object through the telescope, you’ll see it drift slowly across the field of view. To keep it in the field, if your equatorial mount is polar-aligned, just turn the R.A. slow-motion control. The Dec. slow-motion control is not needed for tracking.
a. b. c. d. Figure 10. This illustration shows the telescope pointed in the four cardinal directions: (a) north, (b) south, (c) east, (d) west. Note that the tripod and mount have not been moved; only the telescope tube has been moved on the R.A. and Dec. axes. Figure 10 illustrates how the telescope will look when pointed at the four cardinal directions—north, south, east and west. The key things to remember when pointing the telescope are that a) you only move it in R.A. and Dec.
sary, use the R.A. and Dec. slow-motion controls to re-position the object within the field-of-view of the main telescope’s eyepiece. Focusing the Telescope Practice focusing the telescope in the daytime before using it for the first time at night. Start by turning the focus knob until the focuser drawtube is near the center of its adjustment range. Insert the star diagonal into the drawtube and an eyepiece into the star diagonal (secure with the thumbscrews).
lem that plagues refractor-type telescopes, since light passes through both air and glass to form an image. Most astronomical objects emit a spectrum comprised of many different wavelengths of light, so each wavelength will be bent by a slightly different amount when passing through a lens. This results in each color of light reaching precise focus at a slightly different point, which will provide unacceptable images.
The famous “Double-Double” in the constellation Lyra and the gorgeous two-color double star Albireo in Cygnus are favorites. Defocusing the image of a star slightly can help bring out its color. D. Deep-Sky Objects Under dark skies, you can observe a wealth of fascinating deep-sky objects, including gaseous nebulas, open and globular star clusters, and different types of galaxies. Most deep-sky objects are very faint, so it is important that you find an observing site well away from light pollution.
Deep-sky objects are quite faint, and typically require exposures on the order of 10 minutes. To hold the camera’s shutter open this long, you will need a locking shutter release cable (#5231). Set the camera’s shutter to the “B” (bulb) setting. Depress the locking shutter release cable and lock it. You are now exposing your first deep-sky object. Cleaning the Optics A small amount of dust or a few specks on the glass objective (main) lens will not affect the performance of the telescope.
One-Year Limited Warranty This Orion AstroView 120 Equatorial refractor is warranted against defects in materials or workmanship for a period of one year from the date of purchase. This warranty is for the benefit of the original retail purchaser only. During this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s option, any warranted instrument that proves to be defective, provided it is returned postage paid to: Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076.
