Orion XT8 CLASSIC Aligning the EZ Finder, Replacing the Battery, Aiming/Pointing the Telescope

Naked-eye view

View through and telescope

Figure 11. The view through a reflector telescope is upside

down.

which will lock the focuser drawtube in place once the tele- scope is properly focused.

If you find the drawtube tension when focusing is either too tight (focus knob is difficult to turn) or too loose (image shifts when focusing or drawtube moves inward by itself), the ten- sion can be adjusted for optimal performance. On the XT8 & XT10, the focusing tension adjustment set screw is a 3mm socket head set screw located below the focus lock thumb screw (Figure 10). A 3mm hex key is required for adjustment of focus tension. Due to the rack-and-pinion focuser design on the XT6, tension adjustment should not normally be needed as it has been pre-adjusted at the factory.

Note: The image in the main telescope will appear upside- down (rotated 180°). This is normal for reflector telescopes. (see Figure 11)

Aligning the EZ Finder II

When the EZ Finder II is properly aligned with the telescope, an object that is centered on the EZ Finder II’s red dot should also appear in the center of the field of view of the telescope’s eyepiece. Alignment of the EZ Finder II is easiest during day- light, before observing at night. Aim the telescope at a distant object such as a telephone pole or roof chimney and center it in the telescope’s eyepiece. The object should be at least 1/4 mile away. Now, with the EZ Finder II turned on, look though the EZ Finder II. The object should appear in the field of view.

Without moving the main telescope, use the EZ Finder II’s azi- muth (left/right) and altitude (up/down) adjustment knobs (see Figure 6) to position the red dot on the object in the eyepiece.

When the red dot is centered on the distant object, check to make sure that the object is still centered in the telescope’s field of view. If not, recenter it and adjust the EZ Finder II’s alignment again. When the object is centered in the eyepiece and on the EZ Finder’s red dot, the EZ Finder II is properly aligned with the telescope.

Once aligned, EZ Finder II will usually hold its alignment even after being removed and remounted. Otherwise, only minimal realignment will be ­needed.

Replacing the Battery

Should the battery ever die, replacement 3-volt lithium bat- teries are available from many retail outlets. Remove the old battery by inserting a small flat-head screwdriver into the slot on the battery casing (Figure 6) and gently prying open the case. Then carefully pull back on the retaining clip and remove the old battery. Do not overbend the retaining clip. Then slide the new battery under the battery lead with the positive (+) end facing down and replace the battery casing.

Aiming/Pointing the Telescope

Now that the EZ Finder II is aligned, the telescope can be quickly and accurately pointed at anything you wish to observe. The EZ Finder II has a much wider field of view than the telescope’s eyepiece, and therefore it is much easier to first center an object in the EZ Finder II. Then, if the EZ Finder

IIis accurately aligned, the object will also be centered in the telescope’s field of view.

Start by once again moving the telescope until it is pointed in the general direction of the object you want to see. Some observers find it convenient to sight along the tube to do this. Now, look in the EZ Finder II. If your general aim is accurate, the object should appear somewhere in the EZ Finder II. Make small adjustments to the telescope’s position until the object is centered on the red dot of the EZ Finder. Now, look in the telescope’s eyepiece and enjoy the view!

Magnification

Magnification of the telescope can be changed by using additional eyepieces (optional). To switch eyepieces, simply loosen the thumbscrew(s) on the focuser drawtube and lift the eyepiece out of the focuser. Insert your new eyepiece in the focuser and tighten the thumbscrews. If you are careful not to bump the telescope your object should remain in the field of view. With higher powers notice that the object veing viewed is now larger, but somewhat dimmer.

The SkyQuest is designed to accept any eyepiece with a bar- rel diameter of 1.25". The XT8 and XT10 can also accept 2" eyepieces. Magnification, or power, is determined by the focal length of the telescope and the focal length of the eyepiece. Therefore, by using eyepieces of different focal lengths, the resultant magnification can be varied.

Magnification is calculated as follows:

Magnification= Telescope Focal Length (mm)

Eyepiece Focal Length (mm)

The 6", 8" and 10" SkyQuest Dobsonians all have a focal length of 1200mm. So, the magnification with the supplied 25mm eye- piece is:

1200mm = 48x 25mm

The maximum attainable magnification for a telescope is directly related to how much light its optics can collect. A telescope with

8