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Basic knowledge
V
Basic hints
With the MCX telescopes you can start observing immediately after unpacking. However,
if you have first familiarized yourself with the basics of using the telescope, a subsequent
observation will be much easier and more rewarding.
Eyepiece selection
The task of a telescope eyepiece is to magnify the image produced by the telescope's
main optics. Each eyepiece has a specific focal length, which is specified in millimeters
(mm). The smaller the focal length, the greater the magnification. Low magnification
eyepieces offer a large field of view, bright and high-contrast images and relax your eyes
during longer observation sessions. To adjust an object with the telescope, it is best to
use a slightly magnifying eyepiece - such as the SP 26mm eyepiece supplied with the
MCX. Only when the desired object is set and centered in the center of the field of view
should you switch to an eyepiece with a larger magnification in order to enlarge the image
as far as the current atmospheric conditions allow.
For terrestrial observation we recommend eyepieces with weaker magnification. Dunst,
warm air streaks and suspended particles in the air distort the images when higher
magnifications are used.
For astronomical observations, low or high magnifications may be useful, depending on
the object of observation. Eyepieces with smaller magnifications are used for large-area
observations. On the other hand, high magnifications when observing details on the moon
(e.g. craters) can provide very beautiful images. Even for planets, high magnifications
with good visibility bring the best results.
NOTE!
Seeing conditions change significantly from night to night. Air turbulence, which also
occurs on apparently clear nights, can distort the images permanently. If an image
appears blurry and poorly defined, step back to a lower magnifying eyepiece to achieve a
better resolution (see figure). 26)
What is "magnification"?
The magnification at which a telescope works is determined by two factors: The focal
length of the telescope and the focal length of the eyepiece currently in use.
The focal length of a telescope determines the magnification. Lens telescopes are usually
as long as the focal length. With the mirror-lens combination of an MCX model, however,
this focal length is ultimately extended by the telescope's secondary mirror so that a long
effective focal length can be accommodated in the MCX's short telescope tube. The focal
length of the MCX-127, for example, is 1900 mm. If you had a classic refractor in front
of you, it would mean that its optical tube would have to be more than 1.9 m long - thus
considerably longer than the handy MCX tube length of almost 40 cm with the MCX-127!
The eyepiece focal length stands for the distance the light travels in the eyepiece until
it reaches the focal point. The focal length of the eyepiece is usually indicated on the
side of the eyepiece. The Super Plössl (SP) 26mm eyepiece supplied with the MCX has
a focal length of 26mm. The term "Super Plössl" here stands for the optical design of the
eyepiece, a design specially designed for high-performance telescopes that provides a
large, comfortable field of view combined with extremely high image resolution.
Calculation of the magnification:
A telescope uses different eyepiece focal lengths to
achieve different magnifications. The SP 26mm eyepiece, which is part of the standard
equipment, produces a 73x magnification (73x) with the MCX-127, for example. If you
equip yourself with additional eyepieces from the range of accessories, you will get a
wide variety of magnification options. In addition, you can double the magnification of
the eyepieces used with a 2x Barlow lens (see also "Optional accessories" on page 36).
To calculate the magnification you can achieve with a given eyepiece, use the following
formula:
Telescope focal length
Fig. 26
Example for a too high magnification
(Saturn).
Summary of Contents for MCX Goto Series
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