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The Star Diagonal
The star diagonal diverts the light at a right angle from the light path of the
telescope. For astronomical observing, this allows you to observe in positions
that are more comfortable than if you were to look straight through. To attach the
star diagonal:
Figure 3-2 - The visual accessories
Eyepiece
Visual
Back
Star
Dia
g
onal
1. Turn the thumbscrew on the visual back until its tip no longer extends into (i.e.,
obstructs) the inner diameter of the visual back.
2. Slide the chrome portion of the star diagonal into the visual back.
3. Tighten the thumbscrew on the visual back to hold the star diagonal in place.
If you wish to change the orientation of the star diagonal, loosen the thumbscrew
on the visual back until the star diagonal rotates freely. Rotate the diagonal to the
desired position and tighten the thumbscrew.
The Eyepiece
The eyepiece, or ocular, is the optical element that magnifies the image focused by the telescope. The eyepiece fits into either the visual
back directly or the star diagonal. To install the eyepiece:
1. Loosen the thumbscrew on the star diagonal so it does not obstruct the inner diameter of the eyepiece end of the diagonal.
2. Slide the chrome portion of the eyepiece into the star diagonal.
3. Tighten the thumbscrew to hold the eyepiece in place.
To remove the eyepiece, loosen the thumbscrew on the star diagonal and slide the eyepiece out.
Eyepieces are commonly referred to by focal length and barrel diameter. The focal length of each eyepiece is printed on the eyepiece
barrel. The longer the focal length (i.e., the larger the number) the lower the eyepiece power or magnification; 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. For
more information on how to determine power, see the section on “Calculating Magnification.”
Barrel diameter is the diameter of the barrel that slides into the star diagonal or visual back. The NexStar uses eyepieces with a standard 1-
1/4" barrel diameter.
The Star Pointer Finderscope
The Star Pointer is the quickest and easiest way to point your telescope exactly at a desired object in the sky. It's like having a laser pointer
that you can shine directly onto the night sky. The Star Pointer is a zero magnification pointing tool that uses a coated glass window to
superimpose the image of a small red dot onto the night sky. While keeping both eyes open when looking through the Star Pointer, simply
move your telescope until the red dot, seen through the Star Pointer, merges with the object as seen with your unaided eye. The red dot is
produced by a light-emitting diode (LED); it is not a laser beam and will not damage the glass window or your eye. The Star Pointer comes
equipped with a variable brightness control, two axes alignment control and a quick-release dovetail mounting bracket. Before the Star
Pointer is ready to be used, it must be attached to the telescope tube and properly aligned:
Star Pointer Installation
1. Locate the dovetail mounting bracket on the rear cell of the optical tube.
2. Slide the mounting track at the bottom of the Star Pointer over the dovetail portion of the bracket. It may be necessary to loosen the
two screws on the side of the mounting track before sliding it over the dovetail. The end of the Star Pointer with the glass window
should be facing out towards the front of the telescope.
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