Table of Contents
Advertisement
8. The Meade Model 226W may be used for a lifetime of rewarding astronomical and terrestrial observing,
but basic to your enjoyment of the telescope is a good understanding of the instrument. Read the above
instructions carefully until you understand all of the telescope's parts and functions. One or two observing
sessions will serve to clarify these points forever in your mind.
9. The number of fascinating objects visible through your Meade refractor is limited only by your own
motivation. Obtain a good star atlas (see ''Meade Star Charts" in OPTIONAL ACCESSORIES, page 8)
and read the listings of objects visible through 60mm (2.4") telescopes. These objects include:
•
Cloud belts across the surface of the planet Jupiter.
•
The 4 major moon's of Jupiter, visible around the planet .changing position each night.
•
Saturn and its famous ring system.
•
The Moon: a veritable treasury of craters, mountain ranges and fault lines.
•
Deep-Space: Nebulae, galaxies, multiple star systems, star clusters—hundreds of such objects
are visible through the Model 226W.
•
Terrestrial objects: Your Meade telescope may also be used for high resolution land viewing. In this
case, note that the diagonal prism results in an image which is reversed left-for-right, but which is
correctly oriented up-and-down. For a fully corrected image, the #927 45° Erect Image Roof Prism (.965"
O.D.) is required. See "OPTIONAL ACCESSORIES", page 7. Terrestrial observations should almost
always be made using a low power eyepiece (50X or less) for bright, sharp images. Land objects will not
normally accept higher powers well because the telescope is being pointed through the thickest part of
the Earth's atmosphere, unlike astronomical observations made by pointing the telescope up and through
the atmosphere.
CALCULATING
POWER
The power, or magnification, at which a telescope is operating is determined by two factors: the optical,
or focal length of the telescope's main (objective) lens and the focal length of the eyepiece being used.
The focal length of the Model 226W's objective lens is 700mm. To compute power, divide the focal length
of the eyepiece into the focal length of the objective lens. The resulting quotient is the magnifying power
of the telescope when used with the eyepiece in question. For example, the Kellner 25mm eyepiece
yields with the Model 226W, a power of:
Power = 700mm + 25mm = 28
Similarly, if the Kellner 9mm eyepiece is used, the resulting power will be 700mm
9mm = 77X. The
letter "Ke" refers to the "Kellner" optical design (3-element) which yields very well corrected images with
refracting telescopes and is generally preferred over the more common Huygens, "H", (2-element)
because of its higher quality and better eyerelief for more comfortable viewing. The optical design of the
eyepiece has no bearing on power, however. The Meade Series 2 Orthoscopic eyepieces (4-element)
described in "OPTIONAL ACCESSORES" on page 7 of this manual present extremely sharp, well
resolved images through the Model 226W throughout a wide range of magnifications.
A few words of wisdom
about power. Why not 1000 power or more? Meade is a serious telescope
manufacture known for quality and honest marketing. The theoretical power or magnification with a
telescope is virtually limitless. However, there are practical limits imposed by the earth's atmosphere and
optical resolution as to what can be seen well at a given power. The most often useful higher
magnification with any 60mm diameter telescope is in the range of 90 to 120 power. The general rule to
use with any telescope, regardless of size: Only use as much power as a good image supports: this often
varies with the stability of the air being viewed through and is one reason why having various eyepieces is
useful. Higher powers are no guaranty of better images, in fact the opposite is often true. Meade has
attempted to maximize the performance of your telescope for the most useful power range to provide the
greatest possible utility and enjoyment.
8
Advertisement
Table of Contents
