• 33 •
eyepiece. is movement is caused by the rotation of the Earth. To keep these objects centred in the
eld of the telescope, you just need to turn the right ascension knob (12). You will note that the adjust-
ment knob (13) is only used for centring, and not for tracking.
• Avoid touching the instrument during observation. e resulting vibrations will make the image
move.
• Allow your eyes to adapt to the darkness for a few minutes before starting any serious observation.
Use a torch tted with a red lter to protect your night vision while you examine stellar maps, or while
checking any element of your instrument.
• Avoid setting up the telescope in a room and observing through an open window (or worse, a closed
window). Images obtained this way will appear blurred or misshapen due to the dierence in tempe-
rature between the air indoors and outdoors. Observations should therefore be carried out outdoors,
as far as possible from any urban lighting.
• Avoid observing celestial bodies if they are low on the horizon. e same object, when observed high
in the sky, will appear to have better resolution and contrast when higher up. Equally, turbulence in
the upper atmosphere can make the image «dance» in the eyepiece. Reduce the magnication until
the image appears stable.
Reminder: Warning! Never point the refracting telescope directly at the sun, or even in its sur-
rounding area! Looking at the sun, even for the shortest time, can cause irreversible damage to
your sight, as well as damage to the refracting telescope itself.
e number of fascinating objects that you can observe using your Mizar telescope is only limited by
your own enthusiasm. A good celestial atlas will help you to locate numerous interesting objects.
Among them:
• e Moon: a veritable treasure trove of craters, mountain ranges and fault lines. e best contrast is
obtained during a crescent moon. e contrast will be low during a full moon, due to the illumination
angle.
• Cloud belts on the surface of Jupiter.
• e 4 principal satellites of Jupiter: Io, Europa, Ganymede and Callisto are visible around the planet,
and move every night.
• Saturn and its rings.
• Some objects in the deep sky: nebulae, galaxies...
Remember that given its diameter, this refracting telescope is above all an instrument for planetary
observations.
CALCULATING MAGNIFICATION
e magnication of the refracting telescope is determined by two factors: the focal distance of the re-
fracting telescope and the focal distance of the eyepiece used for any given observation. For example,
the focal distance of the telescope model 70/900 is 900mm. To calculate the magnication, you will
need to divide the focal distance of the objective: F by that of the eyepiece used: f. For example, if you
are using the eyepiece K 25mm with refracting telescope 70/900, the resulting magnication will be:
Magnication = focal distance of the objective / focal distance of the eyepiece = F / f
Magnication = 900mm / 25mm = 36x
