Optional Meade® Accessories; Choosing Eyepieces - Meade ETX-125 Instruction Manual

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

the telescope's main optics. Each eyepiece has a focal
length, expressed in millimeters, or "mm." The smaller
example, an eyepiece with a focal length of 9mm has
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
by the focal length of the telescope and the focal length
divide the telescope's focal length by the eyepiece's
focal length. For example, a 26mm eyepiece is
supplied with the ETX 90. The focal length of the ETX
90 is 1250mm (see SPECIFICATIONS, pages 53 and
54).
Telescope Focal Length 1250mm
Eyepiece Focal Length 26mm
1250 ÷ 26 = 48.1x
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
NOTE: Seeing conditions vary widely from night-to-
44
night and site-to-site. Turbulence in the air, even on
an apparently clear night, can distort images. If an
power eyepiece.
Your telescope comes supplied with a Super Plössl
26mm & 9.7mm eyepiece. These are very good all
purpose eyepieces for your telescope, but you should
consider buying additional eyepieces in longer and
shorter focal lengths to fully realize the potential of the
excellent ETX optical system.
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
are viewing.
You can also use one of the Series 4000 Barlow's to
eyepiece. These eyepieces have been the standard
for over 30 years.