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2. The declination setting circle is factory set and should not need any adjustment if it reads accurately.
3. The right ascension setting circle (#10) must be aligned. Choose a bright and easy to find star in a star chart and note the
coordinates (right ascension and declination). Find the star in the finderscope and then in the telescope. Now, rotate the
right ascension circle to match the coordinates of the star with the indicator mark. If you polar aligned the telescope
accurately, the declination circle should be correctly set to the proper coordinates.
You may notice that there are two sets of numbers on the right ascension dial, one for the northern hemisphere
and one for the southern. Observers in the northern hemisphere should use the upper set of numbers while
southern observers should use the lower set of numbers. Remember in the northern hemisphere, the right
ascension should decrease as the telescope is moved towards the west.
Note
4. The right ascension setting circle does not move as the telescope moves in right ascension and thus it must by aligned
each time you want to use it to find a new object. However, you do not need to use a bright star each time but you can
use the object you are currently observing.
5. Now, using a star chart or atlas you can find numerous objects. First move the telescope in declination to the correct
declination coordinate. Then move the telescope in right ascension until the indicator points to the correct coordinate.
6. After moving the telescope to the correct celestial coordinates, look through the lower power eyepiece to see if you have
located the object you wish to view. Center the object in eyepiece. If the object is not visible in the eyepiece, gradually
pan the telescope, using the right ascension and declination cables, until the object is visible. Always start by using your
lowest power eyepiece (20mm) then switching to higher power once you have found the desired object.
M
M
A
A
G
G
N
N
I
I
F
F
I
I
C
C
A
A
T
T
I
I
O
O
N
N
(
(
P
P
O
O
W
W
E
E
R
R
)
)
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:
Magnification
FL telescope
FL eyepiece
=
()
()
To determine the magnification using the standard 20mm eyepiece, simply divide the focal length of your telescope by the
focal length of the eyepiece (20mm). For example, dividing the focal length of the Firstscope 80 (900mm) by 20mm yields a
magnification of 45 power.
Magnification through the telescope has its limits. These limits are determined by the laws of optics and the nature of the
human eye. The maximum usable power is equal to 60 times the aperture of the telescope (in inches). For example, using
the 80mm model (3.1") then your maximum useful power is 188x (3.1" x 60). You can create power higher than this limit
but the images will be dark and blurred with poor contrast.
The maximum power is used only under ideal conditions which are not common. Most of your viewing will be done in the
range of 25x to 120x. Higher powers are used mainly for lunar and planetary observing under ideal seeing conditions.
D
D
e
e
t
t
e
e
r
r
m
m
i
i
n
n
i
i
n
n
g
g
F
F
i
i
e
e
l
l
d
d
o
o
f
f
V
V
i
i
e
e
w
w
Determining the field of view is important if you want to get an idea of the angular size of the object you are observing. To
calculate the actual field of view, divide the apparent field of the eyepiece (supplied by the eyepiece manufacturer) by the
magnification. In equation format, the formula looks like this:
11