Telescope Basics; Focusing; Aligning The Finder Scope - Celestron Ultima 11 Instruction Manual

Once your telescope is fully assembled, you are ready for your first look. This section deals with some of
the basics of telescope operation.
The image orientation changes depending on how the eyepiece is inserted into the telescope. When using
the star diagonal, the image is right-side-up, but reversed from left-to-right. If inserting the eyepiece
directly into the visual back (i.e., without the star diagonal), the image is upside-down and reversed from
left-to-right (i.e., inverted). This is normal for the Schmidt-Cassegrain design. These orientations apply to
the telescope's finder as well.
The Celestron Ultima focusing mechanism controls the primary mirror which is mounted on a ring that
slides back and forth on the primary baffle tube. The focusing knob, which moves the primary mirror, is on
the rear cell of the telescope just right of the star diagonal and eyepiece. Turn the focusing knob until the
image is sharp. If the knob will not turn, it has reached the end of its travel on the focusing mechanism.
Turn the knob in the opposite direction until the image is sharp. Once an image is in focus, turn the knob
clockwise to focus on a closer object and counterclockwise for a more distant object. A single turn of the
focusing knob moves the primary mirror only slightly. Therefore, it will take many turns (about 40) to go
from close focus to infinity.
For astronomical viewing, out of focus star images are very diffuse making them difficult, if not impossible,
to see. If you turn the focus knob too quickly, you can go right through focus without seeing the image. To
avoid this problem, your first astronomical target should be a bright object (like the Moon or a planet) so
that the image is visible even when out of focus.
Critical focusing is best accomplished when the focusing knob is turned in such a manner that the mirror
moves against the pull of gravity. In doing so, any mirror shift is minimized. For astronomical observing,
both visually and photographically, this is done by turning the focus knob counterclockwise.
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The Ultima 9 / comes with a 6x30 finderscope and the Ultima 11 comes with a 7x50mm finderscope. A
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finderscope helps you aim the main telescope at distant objects that would be hard to find in the narrow
field of the main optics. The first number used to describe the finder is the power or magnification while
the second number is the diameter of the objective lens in millimeters. For example, the Ultima 11 finder is
7x50. This means it is 7 power and has a 50mm objective lens. Incidentally, power is always compared to
the unaided human eye. So a 7 power finder magnifies images seven times more than the human eye. To
make the alignment process a little easier, you should perform this task in the daytime when it is easier to
locate objects in the telescope without the finder. To align the finder:
1. Choose a conspicuous object that is in excess of one mile away. This will eliminate any possible
parallax effect between the telescope and the finder.
2. Point your telescope at the object you selected and center it in the main optics of the telescope.

TELESCOPE BASICS

FOCUSING

ALIGNING THE FINDER SCOPE

Telescope Basics 25