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Attaching the Visual Back
The visual back allows you to attach most visual accessories to the telescope (see Figure 3-7). To attach the visual back:
•
Remove the rubber cover on the rear cell.
•
Place the knurled slip ring on the visual back over the threads on the rear cell.
•
Tighten by rotating the slip ring clockwise until tight.
Once this is done you are ready to attach other accessories such as eyepieces, diagonal prisms, etc.
If you want to remove the visual back, rotate the slip ring counterclockwise until it is free of the rear cell.
Attaching the Star Diagonal
The star diagonal is a prism that 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:
1.
Turn the thumbscrew on the visual back until its tip no longer extends into or 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 diagonal
rotates freely. Rotate the diagonal to the desired position and tighten the thumbscrew. For best results, rotate the diagonal
in the same position as you had it when you did your star alignment. This will maintain pointing accuracy.
Attaching the Eyepiece
The eyepiece, or ocular, is the optical element that magnifies the image focused by the telescope. The eyepiece fits either
into the visual back directly or into the star diagonal. To install an eyepiece into a diagonal:
1.
Loosen the thumbscrews on the star diagonal so that 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 on the diagonal to hold the eyepiece in place.
To remove the eyepiece, loosen the thumbscrew on the star diagonal and slide the eyepiece out.
Barrel diameter is the diameter of the barrel that slides into the star diagonal. Standard barrel diameters are .96”, 1.25”,
and 2”. The Ultima 2000 comes standard for use with 1.25” barrel eyepieces.
In addition to barrel diameter, eyepieces are also referred to in terms of their focal length. 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 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.”
