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Dew shields are useful as they cut stray light entering the telescope, they also protect objective lenses from dew
building up on the optics and also increase contrast. The ARC-152 comes with built-in dew-shield.
Observing the Sun
Special precautions need to be taken when observing the Sun with a telescope. A full aperture Solar filter must be
used to dramatically reduce the amount of light that enters the telescope, only use filters designed to be used for
Solar observation with a telescope. A second filter can also be used at the eyepiece end in conjunction with a full
aperture Solar filter to increase the level of surface detail i.e. Solar Continuum Filters. Such filters work very well
with digital cameras in particular and will reveal additional detail otherwise not visible to the human eye. Always
check the integrity of any Solar filter before using it with a telescope. A hair-line scratch on a filter is enough to
damage your eyesight. If in doubt seek professional advice and never point a telescope towards the Sun without a
suitable Solar filter.
Visual Accessories
Depending on what came with your telescope you may need a number of extra eyepieces which will provide a
wider range of magnifications. For example high magnifications are required for the Moon, planets and planetary
nebulae. Low magnifications are useful for observing extended objects and for locating targets. Ninety degrees star
diagonals are necessary as they make astronomical observation comfortable. For terrestrial observation 45
o
degrees prism diagonals are preferred, such diagonals will also offer a corrected view unlike star diagonals.
A 13% transparency Moon filter will be necessary to observe the Moon with almost all medium to large sized
telescopes including the ARC-152, light pollution filters can also help by reducing sky glow and incoming light
from other local light sources. Finally a 4mm-4.5mm eyepiece is highly recommended for high power viewing of
the Moon and planets.
These telescopes can perform well and as such they will benefit from quality optical accessories including the
Opticstar XL range of premium tele-extenders, Zoom and prime eyepieces as well as the more affordable range of
Opticstar XS eyepieces.
Optics Care
Lenses can be treated as camera lenses for cleaning purposes. What makes them difficult to clean is the large size
of such optical elements. The general rule is not to touch the optics and only clean them when absolutely necessary,
dust on the objective lens could be removed with very gentle strokes of a camel hair brush or with an optics
cleaning cloth available at camera shops.
You can remove condensation from the optics with a hair-dryer set to ‘cold’. Otherwise bring the telescope inside
and let condensation to dissipate before putting on the cover. Place the telescope on a table and not on the floor
where most of the dust can be found. Never try to remove condensation using a cleaning cloth or similar, this will
most likely smear the optics.
Optics Collimation
The telescope comes collimated from the factory. If there was a need the objective could be collimated by an
experienced user, three sets of easily accessible screws allow for precise collimation. Collimation can take place on
a star high up in the sky and under very good atmospheric conditions. Alternatively the telescope can be collimated
or with the aid of an artificial star like the Opticstar Artificial Star XL
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