Celestron C21061 manual Installing the Diagonal & Eyepieces refractor, in above

Installing the Diagonal & Eyepieces ( refractor)

The diagonal is a prism that diverts the light at a right angle to the light path of the refractor. This allows you to observe in a position that is more comfortable than if you looked straight through. This diagonal is an erect image model that corrects the image to be right side up and oriented correctly left-to-right which is much easier to use for terrestrial observing. Also, the diagonal can be rotated to any position which is most favorable for you. To install the diagonal and eyepieces:

1.Insert the small barrel of the diagonal into the 1.25” eyepiece adapter of the focus tube on the refractor – Figure 2-13. Make sure the two thumbscrews on the eyepiece adapter do not protrude into the focuser tube before installation and the plug up cap is removed from the eyepiece adapter.

2.Put the chrome barrel end of one of the eyepieces into the diagonal and tighten the thumb screw. Again, when doing this make sure the thumb screw is not protruding into the diagonal before inserting the eyepiece.

3.The eyepieces can be changed to other focal lengths by reversing the procedure

in step 2 above. Figure 2-13

Installing the Eyepieces on the Newtonians

The eyepiece (or ocular) is an optical element that magnifies the image focused by the telescope. Without the eyepiece it would be impossible to use the telescope visually. Eyepieces are commonly referred to by focal length and barrel diameter. The longer focal length (i.e., the larger the number) the lower the eyepiece magnification (i.e., power). Generally, you will use low-to-moderate power when viewing. For more information on how to determine power, see the section on “Calculating Magnification”. The eyepiece fits directly into the focuser of the Newtonians. To attach the eyepieces:

1.Make sure the thumbscrews are not protruding into the focuser tube. Then, insert the chrome barrel of the eyepieces into the focus tube (remove the plug up cap of the focuser first) and tighten the thumbscrews – see Figure 2-14.

2.The 20mm eyepiece is called an erecting eyepiece since it corrects the

image so it is right side up and corrected left to right. This makes the
telescope useful for terrestrial viewing.	Figure 2-14

3.The eyepieces can be changed by reversing the procedure as described above.

8