Orion XT10 CLASSIC, XT8 CLASSIC Collimation, Tube Balance, Carrying the Telescope

a.

b.

c.

Figure 12. Picking up and carrying the SkyQuest as a single unit (with tube held captive on the base) requires some caution. (a) First, position the tube vertically. Then, grasp the handle on the base with one hand while supporting the tube with the other. (b) With knees bent, slowly lift the base while supporting the tube with one hand. This ensures that the tube will not swing down and impact the ground. (c) As you lift, the whole assembly will tilt down, becoming nearly parallel with the ground, at which time you can let go of the tube with your supporting hand. Make sure you are comfortable with the weight of the whole assembly before attempting to carry it!

more light-collecting area, or aperture, can yield higher mag- nifications than a smaller aperture telescope. The maximum practical magnification for any telescope, regardless of optical design, is about 60x per inch of aperture.This translates to about 360x for the SkyQuest XT6 and 480x for the XT8.

Keep in mind that as magnification is increased, the brightness of the object being viewed will decrease; this is an inherent principle of the physics of optics and cannot be avoided. If magnification is doubled, an image appears four times dim- mer. If magnification is tripled, image brightness is reduced by a factor of nine!

Note About High Magnifications:

Maximum magnifications are achieved only under the most ideal viewing conditions at the best observing sites. Most of the time, magnifications are limited to 200x or less, regardless of aperture. This is because the Earth’s atmosphere distorts light as it passes through. On nights of good “seeing,” the atmo- sphere will be still and will yield the least amount of distortion. On nights of poor seeing, the atmosphere will be turbulent, which means different densities of air are rapidly mixing. This causes significant distortion of the incoming light, which pre- vents sharp views at high magnifications.

Tube Balance

Dobsonians are designed to balance with standard supplied accessories, such as an eyepiece and EZ Finder II. But what if you want to use a larger finder scope or a heavier eyepiece? The telescope will no longer be properly balanced, and will not hold its position properly. This makes the telescope difficult to use, since it is critical that it hold its position (when not pur- posefully moved) to keep objects centered in the field of vision.

Traditional Dobsonian designs expect the user to compen- sate for heavier accessories by adding weight to the opposite end of the telescope tube. Such counterweighting systems can be expensive and unwieldy. The CorrecTension Friction Optimization system of the SkyQuest Dobsonians, however, solves the finicky balance problem. The spring coils pull the tube down onto the base, thereby increasing the friction on the altitude bearing pads. With CorrecTension, the added weight of small front-end loads will not adversely affect the balance of the telescope.

If you install an array of heavier acces- sories onto your SkyQuest’s optical tube, you may need at some point to counterbalance the telescope with a counter- weight system.

Carrying the Telescope

Moving the SkyQuest is easy to do. Because the springs of the CorrecTension system hold the optical tube captive on the base, the entire telescope can be carried as one unit (6" and 8" models only). This requires some caution, however. If the telescope is lifted improperly, the front of the tube could swing down and hit the ground.

First, point the optical tube straight up (vertical). Remove any eyepieces from the telescope and optional eyepiece rack, and place them in an eyepiece case. Grasp the handle on the front of the base with one hand while supporting the telescope tube vertically with the other (see Figure 12). Now, lift the telescope from the handle. Once the telescope is in the horizontal posi- tion, you can carry the entire unit with one hand. The handle position properly balances the load for easy carrying.

If you wish to carry the optical tube and base separately, sim- ply disengage the CorrecTension springs by unhooking them from the posts on the base, using the pull loops. The springs remain captive on the telescope side bearings. Now the base and tube are disengaged and can be transported separately.

Note: The SkyQuest may be too heavy for some users to lift and carry as one unit. Do not strain yourself! If the load seems too heavy, disengage the springs and carry the base and tube separately.

When putting the SkyQuest into a vehicle, common sense pre- vails. It is especially important that the optical tube does not knock around; this can cause the optics to become misaligned, and could dent the tube. We recommend transporting and stor- ing the tube assembly in a padded case for proper protection.

4. Collimation

Collimation is the process of adjusting the mirrors so they are correctly aligned with one another. Your telescope’s optics were aligned at the factory, and should not need much adjust- ment unless the telescope is handled roughly. Accurate mirror

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