Meade EXT90 - Optional MEADE Accessories; ETX90 Key Features; Telescope; Optional Accessories

Series 4000 Super Plössl Eyepieces
40.0mm SP 44º 31x 1.41°
32.0mm SP 52º 39x 1.33º
26.0mm SP 52º 48x 1.08°
20.0mm SP 52º 63x .83°
15.0mm SP 52º 83x .62°
12.4mm SP 52º 101x .52°
9.7mm SP 52º 129x .40°
6.4mm SP 52º 195x .27°
Focal Apparent True
Length Type Field Power Field
OPTIONAL ACCESSORIES
Meade makes a complete line of accessories to enable
you to get the most fun and performance from your
ETX Series telescope. No matter what you want to
accomplish, we have the equipment to help you get
there.
Choosing Eyepieces
A telescope’s eyepiece magnies the image formed by
the telescope’s main optics. Each eyepiece has a focal
length, expressed in millimeters, or “mm.” The smaller
the focal length, the higher the magnication. For
example, an eyepiece with a focal length of 9mm has
a higher magnication than an eyepiece with a focal
length of 26mm. Experienced users know that higher
powers are, in general, not as useful as lower powers.
Many of the objects in the night sky are relatively large
and faint and look best at low magnications.
The power or magnication of a telescope is determined
by the focal length of the telescope and the focal length
of the eyepiece being used. To calculate magnication,
divide the telescope’s focal length by the eyepiece’s
focal length. For example, a 26mm eyepiece is supplied
with the ETX90. The focal length of the ETX90 is
1250mm (see SPECIFICATIONS, pages 48 and 49).
Telescope Focal Length 1250mm
Eyepiece Focal Length 26mm
1250 ÷ 26 = 48.1x
The magnication is therefore 48.1x.
Low power eyepieces offer a wider eld of view, bright,
high-contrast images, and long eye relief. To nd an
object with a telescope, always start with a lower power
eyepiece such as the Super Plössl 26mm or longer
focal length. When the object is located and centered
in the eyepiece, you may wish to switch to a higher
power eyepiece to enlarge the image as much as
practical for prevailing seeing conditions or, for many
objects, the view is best with a high quality low-power
wide-eld eyepiece.
NOTE: Seeing conditions vary widely from night-to-
night and site-to-site. Turbulence in the air, even on
an apparently clear night, can distort images. If an
image appears fuzzy and ill-dened, reduce to a lower
power eyepiece.
Your telescope comes supplied with a Super Plössl
26mm eyepiece, which gives a wide 1.08 degree eld
of view with 48x magnication. This is a very good all
purpose eyepiece for your telescope, but you should
consider buying additional eyepieces in longer and
shorter focal lengths to fully realize the potential of
the excellent 90mm optical system in your ETX90
telescope.
The Series 4000 Super Plössl Eyepieces are excellent
well corrected 4 element optics at popular prices. They
come in a wide range of focal lengths to give you the
right magnication for any type of celestial object you
are viewing. You can also use one of the Series 4000
Barlows to double or triple the magnication of a Super
Plössl eyepiece. These eyepieces have been the
standard for over 30 years.
OPTIONAL ACCESSORIES
17