drawtube
Reflection of primary mirror clip
a.
Reflective surface | Primary mirror |
of collimation | center mark |
cap |
|
b.c.
d.e.
Figure 35. 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 center “dot” of the collimation cap will be centered in the ring on the primary mirror, as in (e).
3.Aligning (Collimating) the Optical System
Collimating is the process of adjusting the mirrors so they are aligned with one another.Your telescope’s optics were aligned at the factory, and should not need much adjustment unless the telescope was handled roughly in transit. Accurate mir- ror alignment is important to ensure the peak performance of your telescope, so it should be checked regularly. Collimating is a relatively easy process and can be done in daylight or darkness.
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 35a. If anything is
The Collimation Cap
Your XX14i comes with a “quick collimation cap” (Figure 36). This is a simple cap that fits on the focuser drawtube like a dust cap, but has a tiny hole in the center and a reflective inner surface. The collimation cap helps center your eye over the focuser drawtube so that aligning the optical components is easier to achieve. The reflective surface provides a distinct visual reference that is helpful in centering the mirror reflec- tions. Figures 35b through 35e assume that you have the collimation cap in place.
Figure 36. The included “quick collimation cap” has a hole in the center and a reflective inner surface.
The Primary Mirror Center Mark
You’ll notice that the primary mirror of the XX14i has a small adhesive ring marking its center. This “center mark” allows you to achieve a very precise collimation; you don’t have to guess where the exact center of the mirror is.
NOTE: The center ring sticker need not ever be removed from the primary mirror. Because it lies directly in the shadow of the secondary mirror, its presence in no way adversely affects the optical performance of the telescope or the image quality. That might seem counterintuitive, but it’s true!
Preparing the Telescope for Collimating
Once you get the hang of collimating, you will be able to do it quickly even in the dark. For now, it is best to collimate in daylight, preferably in a brightly lit room and aimed at a light- colored wall. It is recommended that the telescope tube be oriented horizontally. This will prevent any parts from the secondary mirror from falling down onto the primary mirror
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