Orion XT10 CLASSIC, XT8 CLASSIC Using Your Telescope, Inserting an Eyepiece, Altitude and Azimuth

Altitude

Azimuth

Figure 9. The SkyQuest has two axes of motion: altitude (up/ down) and azimuth (left/right).

The CorrecTension system is now installed and engaged. If you wish to remove the telescope from the base, you will first need to disconnect the springs from the “posts” on the Dobsonian base. The springs will remain captive on the alti- tude side bearings, so they will not get lost.

Inserting an Eyepiece

The final step in the assembly process is to insert an eyepiece into the telescope’s focuser. Take the cover cap off the end of the focuser drawtube.

For the XT6: Loosen the two thumbscrews on the eyepiece holder and insert the eyepiece. Then secure it in place with the thumbscrews.

For the XT8 and XT10: There are three thumbscrews on the focuser, one holds the eyepiece, and two hold the 1.25" adapter. To insert the eyepiece, loosen the thumbscrew that is on the 1.25" adapter itself (it will be highest up on the focuser). Insert the eyepiece into the adapter and secure it by tighten- ing the thumbscrew.

The assembly of your SkyQuest Dobsonian is now complete. It should appear as in Figure 1. The dust cover on the front of the telescope should always remain in place when the tele- scope is not in use. It is also a good idea to store eyepieces in an eyepiece case and to replace the cover cap on the focuser when the telescope is idle.

3. Using Your Telescope

It is best to get a feel for the basic functions of the SkyQuest Dobsonian during the day, before observing astronomical objects at night. This way you will not have to fumble around

2" eyepiece adapter

Focus knobs 1.25" eyepiece

adapter

Focus lock thumbscrew

Tension adjustment screw

Figure 10. The 2" Crayford focuser (XT8 and XT10)

trying to orient yourself in the dark! Find a spot outdoors where you have plenty of room to move around the telescope, and where you have a clear view of some object or vista that is at least 1/4-mile away. It is not critical that the base be exactly level, but it should be placed on somewhat flat ground or pave- ment to ensure smooth movement of the telescope.

Remember, never point the telescope at or near the Sun without using a proper solar filter over the front aperture!

Altitude and Azimuth

The Dobsonian base of the SkyQuest permits motion of the telescope along two axes: altitude (up/down) and azimuth (left/right) (Figure 9). This is very convenient, since up/down and left/right are the most “natural” ways that people aim. As a result, pointing the telescope is exceptionally easy.

Simply take hold of the end of the tube and move it left or right so the base rotates about its central azimuth bolt, and move it up or down so the altitude side bearings rotate in the base’s cradle. Both motions can be made simultaneously and in a continuous manner for easy aiming. Move the telescope gently—let it glide. In this way you can point the telescope to any position in the night sky, from horizon to horizon.

Focusing the Telescope

Insert the 25mm eyepiece into the focuser and secure with the thumbscrew(s). Move the telescope so the front (open) end is pointing in the general direction of an object at least 1/4-mile away. Now, with your fingers, slowly rotate one of the focusing knobs 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’ve hit the exact focus point.

If you have trouble focusing, rotate the focusing knob so the drawtube is in as far as it will go. Now look through the eye- piece while slowly rotating the focusing knob in the opposite direction. You should soon see the point at which focus is reached.

The 2" Crayford focuser of the XT8 and XT10 models features a thumb screw on the bottom of the focuser body (Figure 10)

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