Orion 9966 instruction manual Collimation Aligning The Mirrors, Transporting the Telescope

Figure 19. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (b) With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (c) Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible. (d) The secondary mirror is correctly

aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned, the “dot” will be centered, as in (e).

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 XT12 Dobsonian, however, solves the finicky bal- ance 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 XT12’s optical tube, you may need at some point to counterbalance the telescope with a counterweight system.

Transporting the Telescope

Even though it is a larger-aperture instrument, transporting the SkyQuest XT12 is relatively easy. Remove any eye- pieces from the telescope and eyepiece rack, and place them in an eyepiece case. You can also remove the finder scope and finder scope bracket, if you wish. 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. The base and tube are now disengaged and can be transported separately.

The tube is somewhat heavy, so don’t hesitate to have a friend help lift the tube, if necessary. Do not use the naviga- tion knob as a carry handle! It is not designed to support the weight of the telescope tube and could break off or damage the tube. To carry the base, simply grasp the handle on the front of it.

When putting the SkyQuest XT12 into a vehicle, common sense prevails. 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 trans- porting and storing the tube assembly in a padded case for proper protection.

4.Collimation (Aligning The Mirrors)

Collimation is the process of adjusting the mirrors so they are properly 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 alignment is important to ensure the peak performance of your telescope, so it should be checked regularly. Collimation is relatively easy to do and can be done in daylight.

To check collimation, remove the eyepiece and look down the focuser drawtube. You should see the secondary mirror cen- tered in the drawtube, as well as the reflection of the primary mirror centered in the secondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror, as in Figure 19a. If anything is off-cen- ter, as in Figure 19b, proceed with the following collimation procedure.

The Collimation Cap and Mirror Center Mark

Your SkyQuest XT12 comes with a collimation cap. This is a simple cap that fits on the focuser drawtube like a dust cap, but

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