Celestron Advanced Series C8-N User Manual download pdf (Page 12)

the eyepiece out. You can replace it with another ocular.

Eyepieces are commonly referred to by focal length which is printed on the

eyepiece barrel. The longer the focal length (i.e., the larger the number) the

lower the eyepiece power and the shorter the focal length (i.e., the smaller the

number) the higher the magnification. Generally, you will use low-to-

moderate power when viewing.

Your telescope can use eyepieces with both a 1-1/4" barrel diameter and 2"

barrel diameter. To use a 2" barrel eyepiece, the 1 1/4" eyepiece adapter must

first be removed and replaced with the included 2" eyepiece adapter. To do

this, simply loosen the two chrome thumbscrews located around the focuser

barrel (see figure 2-12) and remove the 1 1/4" adapter. Once removed, a 2"

eyepiece adapter can be inserted directly into the focuser barrel and secured with the

two thumb screws.

To eliminate undue stress on the mount, the telescope should be properly balanced around the polar axis. In

addition, proper balancing is crucial for accurate tracking if using an optional motor drive. To balance the mount:

1. Release the R.A. Clamp (figure 2-16) and position the telescope off to one side of the mount (make sure that the

mounting bracket screw is tight). The counterweight bar will extend horizontally on the opposite side of the mount

(see figure 2-13).

2. Release the telescope — GRADUALLY — to see which way the telescope “rolls.”

3. Loosen the set screw on the counterweight.

4. Move the counterweight to a point where it balances the telescope (i.e., it remains stationary when the R.A. clamp is

released).

5. Tighten the set screw to hold the counterweight(s) in place.

These are general balance instructions and will reduce undue stress on the mount. When taking astrophotographs,

this balance process should be done for the specific area at which the telescope is pointing.

Balancing the Telescope in DEC

The telescope should also be balanced on the declination axis to prevent any sudden motions when the DEC clamp

(figure 2-16) is released. To balance the telescope in DEC:

1. Release the R.A. clamp and rotate the telescope so that it is on one side of the mount (i.e., as described in the

previous section on balancing the telescope in R.A.).

2. Lock the R.A. clamp to hold the telescope in place.

3. Release the DEC clamp and rotate the telescope until the tube is parallel to the ground (see figure 2-14).

4. Release the tube — GRADUALLY — to see which way it rotates around the declination axis. DO NOT LET GO

OF THE TELESCOPE TUBE COMPLETELY!

2" Eyepiece

Adapter

ure 2-12

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Celestron Advanced Series C8-N User Manual Page 12