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Image as seen when using the
erect image diagonal
Focusing
To focus your telescope, simply turn the focus knob located directly below the eyepiece holder. Turning the knob clockwise
allows you to focus on an object that is farther than the one you are currently observing. Turning the knob counterclockwise
from you allows you to focus on an object closer than the one you are currently observing.
•
If you wear corrective lenses (specifically glasses), you may want to remove them when observing with an eyepiece
attached to the telescope. However, when using a camera you should always wear corrective lenses to ensure the
sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times.
•
Avoid looking through glass. Glass found in household windows is optically imperfect, and as a result, may vary in
thickness from one part of a window to the next. This inconsistency can and will affect the ability to focus your
telescope. In most cases, you will not be able to achieve a truly sharp focus. In some cases, you may actually see a
double image.
•
Never look across or over objects producing heat waves. This includes asphalt parking lots on hot summer days or
building rooftops.
•
Hazy skies, fog, and mist can also make it difficult to focus when viewing terrestrially. The amount of detail that
can be seen under these conditions will be greatly reduced. Also, when photographing under these conditions, the
processed film may come out a little grainier than normal.
•
When using your telescope as a telephoto lens, the split screen or microprism focuser of the 35mm camera may
"black out." This is common with all long focal length lenses. If this happens, use the ground glass portion of your
focusing screen. To achieve a very sharp focus, you may consider using a focusing magnifier. These are readily
available from your local camera store.
M
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The magnification (or power) of a telescope is variable depending upon the focal length of the eyepiece being used along
with the focal length of the telescope. In equation format, the formula looks like this:
O
N
(
P
O
W
E
R
)
O
N
(
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)
Magnification
Inverted image, as viewed with
the eyepiece directly in telescope
Figure 6
FL telescope
(
)
=
FL eyepiece
(
)
6
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