Celestar Manual
Telescope Basics
24
FOCUSING
The Celestar 8 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 (approximately 25 feet) to infinity.
For astronomical viewing, out of focus star images are very diffuse, making them difficult 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.
ALIGNING THE FINDER
The Celestar 8 comes with a 6x30mm finder (9x50mm for Celestar Deluxe 8) which 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 Celestar 8 finder is a 6x30. This means it is 6 power
and has a 30mm objective lens. Incidentally, power is always compared to the unaided human eye. So a 6
power finder magnifies images six 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.
3.
Lock the R.A. and DEC clamps to hold the telescope in place.
4.
Check the finder to see where the object is located in the field of view.
5.
Adjust the black thumb screws on the finder bracket, tightening one while loosening another, until the
cross hairs are centered on the target.
6.
Tighten each black thumb screw a quarter of a turn to ensure that they will not come loose easily.
The image orientation through the finder is inverted (i.e., upside down and reversed from left-to-right).
Because of this, it may take a few minutes to familiarize yourself with the directional change each screw
has on the finder.
Содержание Celestar 8
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Страница 4: ...Celestar Manual 4 TECHNICAL SPECIFICATIONS 78 FURTHER READING 79 ...
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