Meade Instruments Infinity 70AZ - Manual (Page 14)

exposure. f/5 is faster than f/10. The
faster the ratio, the faster exposure time
is needed when a camera is hooked up
to the telescope. Your telescope has
slower focal ratio at f/8.5. Sometimes,
astronomers use focal reducers to make
slow exposure telescopes have faster focal
ratios.
Alt-azimuth mounting simply means your
telescope moves up and down (altitude
or “alt”), and side to side, (azimuth or “az”).
Other mounting configurations are available
for other telescopes, such as equatorial
mounting.
USE THE SPECIFICATIONS TO CALCU-
LATE THE MAGNIFICATION OF YOUR
EYEPIECE
The power of a telescope is how much it
magnifies objects. For a Infinity 70, the
26mm eyepiece magnifies an object 27
times. The 9mm eyepiece magnifies objects
78 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
70, you will see that the focal length of your
scope is 700mm. 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: 700 ÷ 13, which equals 54.85.
Round this off to the nearest whole number
12
and your new eyepiece magnifies objects 55
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 70 the 26mm low-power eye-
piece magnifies an object 27 times. Multiply
27 by 2 and you get 54 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
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.