FOCUSING ON A CELESTIAL OBJECT
Focusing on a celestial object is similar to focusing on an earthly
object, except that it is always moving. Therefore, when focusing
on an object, adjustment can not always be repeated for the next
target. We recommend that you adjust focus regularly, as it can
easily be modified by various factors (temperature changes of the
optics, movements of the telescope, unintentional changes by the
observer, etc.).
To make observation easier, adjust the focus at the very beginning
by aiming at a bright object, such as the Moon, a planet, or a bright
star. It can be difficult for beginners to directly find the focus range
for faint objects in the deep sky and / or for those located in a field
with few or faint stars.
MAGNIFICATION CHOICE
15. The choice of magnification depends on the type of object being
observed and the technical specifications of the telescope. The
STELESCOPE 70 comes with two eyepieces with focal lengths of 20
and 9 mm, which deliver magnifications of 45 and 100 times (see also
p.11 for magnification calculations). It can withstand magnifications
of up to about 150 times, provided that the appropriate eyepieces
are obtained and that the quality of the sky allows it.
As a general rule:
• the lowest magnification is used when searching for a target;
• the target is well centered in the eyepiece before changing to a
higher magnification;
• magnifying beyond the maximum value accepted by the
telescope has no purpose;
• the highest magnification is not necessarily the best for quality
observation;
• magnification tends to darken the image and reduce the field
of view;
• when the atmosphere is turbulent (stars are twinkling), there
is no purpose for increased magnification, as this only leads to
blurred images.
In order to choose the right magnification according to the star
being observed, keep in mind that:
• the Moon, the planets, and all bright targets can more easily
withstand high magnifications (when the atmosphere is
sufficiently stable and they are not too low on the horizon);
• deep sky objects are best viewed at low to medium
magnifications, unless they are very small.
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