Instruction manual

14
Figure 3-4 Figure 3-5
To align the Star Pointer finderscope:
1. To turn on the Star Pointer, turn the switch to the “on” position – see Figure 3-4.
2. Locate a bright star or planet and center it in a low power eyepiece in the main telescope.
3. With both eyes open, look through the glass window at the alignment star.
If the Star Pointer is perfectly aligned, you will see the red LED dot overlap the alignment star. If the Star Pointer is not
aligned, take notice of where the red dot is relative to the bright star.
4.Without moving the main telescope, turn the Star Pointer's two adjustment screws until the red dot is directly over the
alignment star. Experiment as to which way each screw moves the red dot.
5. The Star Pointer is now ready for use. Always turn the power off after you have found an object. This will extend
the life of both the battery and the LED.
Note: Your battery may be installed already. If not, open the battery compartment – see Figure 3-4 with a thin coin
or screwdriver. Put the battery in with the “+” sign facing out. Then put the battery compartment back on. If you
ever need to replace the battery, it is a 3-volt lithium type # CR 1620.
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You can change the power of your telescope just by changing the eyepiece (ocular). To determine the
magnification of your telescope, simply divide the focal length of the telescope by the focal length of the eyepiece
used. In equation format, the formula looks like this:
Focal Length of Telescope (mm)
Magnification = 
Focal Length of Eyepiece (mm)
Let’s say, for example, you are using the 20mm eyepiece that came with your telescope. To determine the
magnification you simply divide the focal length of your telescope (the AstroMaster 90EQ for this example has a
focal length of 1000mm) by the focal length of the eyepiece, 20mm. Dividing 1000 by 20 yields a magnification of
50 power.
Although the power is variable, each instrument under average skies has a limit to the highest useful magnification. The general
rule is that 60 power can be used for every inch of aperture. For example, the AstroMaster 90EQ is 3.5” inches in diameter.
Multiplying 3.5 by 60 gives a maximum useful magnification of 210 power. Although this is the maximum useful magnification,
most observing is done in the range of 20 to 35 power for every inch of aperture which is 70 to 123 times for the AstroMaster
90EQ telescope. You can determine the magnification for your telescope the same way.
On/Off
Switch
Battery Compartment