Orion SKYQUEST XT6 User Manual download pdf (Page 9)

1200mm

= 48x

25mm

The magnification provided by the 10mm eyepiece is

1200mm

= 120x

10mm

The maximum attainable magnification for a telescope is directly

related to how much light its optics can collect. A telescope with

more light-collecting area, or aperture, can yield higher magnifi-

cations 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

atmosphere will be still and will yield the least amount of dis-

tortion. 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 prevents sharp views at high magnifications.

Tube Balance

Dobsonians are designed to balance with standard supplied

accessories, such as an eyepiece and a finder scope. 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 compensate

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 accessories onto your

SkyQuest’s optical tube, you may need at some point to coun-

terbalance the telescope with a counterweight 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. 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 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 verti-

cally with the other (see Figure 11). 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.

Figure 11. 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!

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Orion SKYQUEST XT6 User Manual Page 9

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