Instruction manual

times. The 9mm eyepiece magnifies objects
66.7 times.
If you obtain other eyepieces, you can calcu-
late how much magnification they have with
your telescope. Just divide the focal length
of the telescope by the focal length of the
eyepiece.
Focal Length of the Telescope
÷
Focal Length of the Eyepiece
=
Magnification
Look at the specifications. For the Infinity
90, you will see that the focal length of this
scope is 600mm. Let’s say that you have
obtained a 13mm eyepiece. You can tell that
what the focal length of your eyepiece is as
it is always printed on the side of an eye-
piece. Divide: 600 ÷ 13, which equals 46.15.
Round this off to the nearest whole number
and the new 13mm eyepiece magnifies
objects 46 times.
A great accessory for your telescope is
a Barlow lens If you use a Barlow lens
with one of your eyepieces, it doubles the
magnification of your eyepiece. Other types
of Barlows can triple or further increase the
power of an eyepiece. To find out how much
the magnification is when you use a Barlow,
multiply your eyepiece’s magnification
by two.
Eyepiece’s magnification x 2
=
Magnification with a 2X Barlow lens
For the Infinity 90 the 26mm low-power eye-
piece magnifies an object 23 times. Multiply
23 by 2 and you get 46 times magnification
with a Barlow.
It’s worth repeating: Keep in mind that a
bright, clear, but smaller image is more
interesting than a larger, dimmer, fuzzy one.
Using too high a power eyepiece is one of
the most common mistakes made by new
astronomers. So don’t think that higher
magnification is necessarily better—quite
often the best view is with lower magnifica-
tion value!
TAKING CARE OF YOUR TELESCOPE
Your telescope is a precision optical instru-
ment designed for a lifetime of reward-
ing viewing. It will rarely, if ever, require
factory servicing or maintenance.
Follow these guidelines to keep your
telescope in the best condition:
• Avoid cleaning the telescope’s lenses.
A little dust on the front surface of the
telescope’s correcting lens will not cause
loss of image quality.
• When absolutely necessary, dust on the
front lens should be removed with very
gentle strokes of a camel hair brush or
blown off with an ear syringe (available
at most pharmacies).
Looking at or near the Sun will cause irreversible damage to your eye. Do not point this telescope at or near the Sun. Do not look through the telescope as it is moving.
JOIN AN ASTRONOMY CLUB, ATTEND A STAR
PARTY
One of the best ways to increase your knowledge of
astronomy is to join an astronomy club. Check your
local newspaper, school, library, or telescope dealer/
store to find out if there’s a club in your area.
Many groups also hold regularly scheduled Star
Parties at which you can check out and observe
with many different telescopes and other pieces of
astronomical equipment. Magazines such as Sky and
Telescope and Astronomy print schedules for many
popular Star Parties around the United States and
Canada.
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