Figure 9a |
| Figure 9b |
|
|
|
Figure 9a,b,c,d: This illustration shows the telescope pointed in
the four cardinal directions: (a) North, (b) South, (c) East, (d) West.
Figure 9c |
| Figure 9d |
|
|
|
Note that the tripod and mount have not been moved; only the telescope tube has move on the R.A. and Dec. axis.
scope on the R.A. axis until the counterweight shaft is hori- zontal (parallel to the ground). Then loosen the Dec. lock lever and rotate the telescope until it is pointing straight overhead. The counterweight shaft is still horizontal. Then retighten both lock levers.
What if you need to aim the telescope directly north, but at an object that is nearer to the horizon than Polaris? You can’t do it with the counterweight down as pictured in Figure 1. Again, you have to rotate the scope in R.A. so that the counterweight shaft is positioned horizontally. Then rotate the scope in Dec. so it points to where you want it near the horizon.
To point the telescope directly south, the counterweight shaft should again be horizontal. Then you simply rotate the scope on the Dec. axis until it points in the south direction.
To point the telescope to the east or west, or in other direc- tions, you rotate the telescope on its R.A. and Dec. axes. Depending on the altitude of the object you want to observe, the counterweight shaft will be oriented somewhere between vertical and horizontal.
Figure 9 illustrates how the telescope will look when pointed at the four cardinal directions: north, south, east and west.
The key things to remember when pointing the telescope are that a) you only move it in R.A. and Dec., not in azimuth or latitude (altitude), and b) the counterweight and shaft will not always appear as it does in Figure 1. In fact it almost never will!
5.Collimation (Aligning the Mirrors)
Collimation is the process of adjusting the mirrors so they are perfectly 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 mir- ror 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 10a. If anything is
The Collimation Cap and Mirror Center Mark
Your AstroView 6 EQ comes with a collimation cap. This is a simple cap that fits on the focuser drawtube like a dust cap, but has a hole in the center and a silver bottom. This helps center your eye so that collimation is easy to perform. Figures 10b through 10e assume you have the collimation cap in place.
In addition to the collimation cap, the primary mirror is marked with a circle at its exact center. This “center mark” allows you to achieve a precise collimation of the primary mirror; you don’t have to guess where the center of the mirror is. You simply adjust the mirror position (described below) until the reflection of the hole in the collimation cap is centered in the ring. The center mark is also required for best results when using other collimating devices, such as Orion’s LaserMate Collimator, obviating the need to remove the primary mirror and mark it yourself.
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 tele- scope or the image quality.That might seem counterintui- tive, but its true!
Aligning the Secondary Mirror
With the collimation cap in place, look through the hole in the cap at the secondary (diagonal) mirror. Ignore the reflections for the time being. The secondary mirror itself should be cen- tered in the focuser drawtube, in the direction parallel to the length of the telescope. If it isn’t, as in Figure 10b, it must be adjusted. Typically, this adjustment will rarely, if ever, need to be done. It helps to adjust the secondary mirror in a brightly lit room with the telescope pointed towards a bright surface, such as white paper or wall. Also placing a piece of white paper in the telescope tube opposite the focuser (in other words, on the other side of the secondary mirror) will also be helpful in collimating the secondary mirror. Using a 2mm Allen wrench, loosen the three small alignment set screws in the center hub of the
11
