Barska 300 Power Starwatcher Telescope 40070, User Manual

Page: 4 / 5

the moon an object that is relatively close and exceptionally bright, so that good detail
resolution is achieved at high magnification ratios.
Magnification within any telescope has its limits. These limits are determined by the laws
of optics and the nature of the human eye. Most viewing will be done in the range of 30x to
100x. Higher powers are used mainly for lunar and sometimes planetary observing where
you can greatly enlarge the image and the atmospheric conditions are near perfect. The
images at extremely high powers magnify the image, but the contrast will be very low due
to the high magnification. For the brightest images with the most contrast, start by using the
lower power eyepiece with a smaller image scale.
The formula used to calculate the magnification of a telescope is:
Focal length of the telescope in mm / Focal length of the eyepiece in mm = Magnification
Example: 400mm Focal length telescope / 4mm Focal length of eyepiece = 100x
magnification
The following magnification levels can be achieved when using the included SR4 or K20
eyepiece and in conjunction with the 3x Barlow lens:
Telescope
Focal Length (FL)
Eyepiece
Focal Length (FL)
Magnification
Magnification with
3x Barlow Lens
400mm SR4 4mm 100x 300x
400mm K20 20mm 20x 60x
BARLOW LENS
The included 3x Barlow lens triples the magnifying power of each eyepiece. The highest
magnification power of the Barlow lens should only be used for large and bright objects
such as the moon and the brightest planets, as well as for nights with optimal observation
conditions.
Attaching and Using the Barlow Lens
1. Insert the barlow lens directly into
the diagonal and tighten the
thumb screw on the diagonal.
3. Loosen the thumb screw of the
Barlow lens and start by using the
K20 eyepiece, and insert it directly
into the barlow lens and tighten the
thumb screw.
4. Focusing is then completed in the
customary manner See Focusing page 5
NOTES ON VIEWING
WARNING
CAUTION: DO NOT LOOK DIRECTLY AT THE SUN VIEWING THE SUN OR ANY LIGHT
SOURCE WITH THIS OPTICAL DEVICE CAN CAUSE PERMANENT EYE DAMAGE.
Looking at or near the sun will cause instant and irreversible damage to your eye(s).
Eye damage is often painless, there is no warning to the observer that the damage has
occurred until it is too late. Do not point the telescope at or near the sun. Children should
always have an adult supervising when using this optical product
While observing through the telescope avoid touching the eyepiece or placing the tripod on
uneven ground. Vibrations can cause the image in the telescopic field of view to move.
When observing at night allow a few minutes for your eyes to become “dark adapted” prior
to observations. Use a red-filtered flashlight to protect your night vision when reading star
maps, or inspecting components of the telescope.
Allow your telescope a chance to reach the surrounding temperature before observing.
Avoid setting up the telescope inside a room and observing through an open window.
Temperature differences between inside and outside air may result in images appearing
blurred or distorted due to temperature differences between inside and outside air.
Avoid looking across objects that produce heat waves, such as asphalt parking lots during
the day. Images viewed may appear blurry or distorted
ROTATION OF THE EARTH
Please note if you are observing a celestial object (a planet, the Moon, a star, etc.) the
object is in a rather slow but continuous motion through the telescopic field of view. This
motion or movement is caused by the rotation of the Earth on its axis which results in an
apparent motion of the object in the telescope’s field of view for example a planet, the
Moon, a star, for practical purposes, are fixed in their positions during any 2 or 3 hour
observing period, the stand on which the telescope is sitting (the Earth) rotates once every
24 hours underneath these fixed objects. To keep astronomical objects centred in the field,
simply move the telescope on one or both of its axes (vertical and/or horizontal) as needed.
At lower powers, astronomical objects will seem to move through the field slowly through
the telescopic field of view. At higher powers, astronomical objects will seem to move
through the telescopic field more rapidly.
CARE AND CLEANING
With proper care, your telescope should rarely need any maintenance work. To maintain
your telescope in the best possible condition, observe the follow suggestions:
NEVER attempt to clean the telescope internally or try to take it apart.
When not in use, replace all covers to keep dust and contaminants off the optical surfaces.
Store in a cool, dry place
Blow away any dust or debris on the lens (or use a soft lens brush)
To remove dirt or fingerprints, clean with a soft cotton cloth rubbing in a circular motion.
Use of a coarse cloth or unnecessary rubbing may scratch the lens surface and eventually
cause permanent damage.
300 Power, 40070 Starwatcher Telescope 300 Power, 40070 Starwatcher Telescope
6 7
Attaching the Barlow Lens
Eyepiece
▼
Barlow Lens
▼
Diagonal