Instruction manual

10
Fig.e
U
sing the optional Barlow lens
A Barlow is a negative lens which increases the
magnifying power of an eyepiece, while reducing the field
of view. It expands the cone of the focussed light before it
reaches the focal point, so that the telescope's focal length
appears longer to the eyepiece.
The Barlow is inserted between the focuser and the
eyepiece in a reflector, and usually between the diagonal
and the eyepiece in a refractor or a maksutov (Fig.e). With
some telescopes, it can also be inserted between the
focuser and the diagonal, and in this position it gives even
greater magnification. For example, a 2X Barlow when
inserted after the diagonal can become 3X when placed in
front of the diagonal.
In addition to increasing magnification, the benefits of
using a Barlow lens include improved eye relief, and
reduced spherical aberration in the eyepiece. For this
reason, a Barlow plus a lens often outperform a single lens
producing the same magnification. However, its greatest
value may be that a Barlow can potentially double the
number of eyepieces in your collection.
Barlow
Diagonal
Eyepiece
(Refracting Telescopes
and Maksutovs)
(Refracting Telescopes)
(Reflecting Telescopes)
(Reflecting Telescopes)
Barlow
Eyepiece
F
ocusing
Fig.f
Slowly turn the focus knobs under the focuser, one way or
the other, until the image in the eyepiece is sharp (Fig.f).
The image usually has to be finely refocused over time,
due to small variations caused by temperature changes,
flexures, etc. This often happens with short focal ratio
telescopes, particularly when they have not yet reached
outside temperature. Refocusing is almost always
necessary when you change an eyepiece or add or
remove a Barlow lens. On some focusers, there is a
tension adjustment. Over-tighten this may damage the
rack and pinion assembly.
The pole-finder telescope supplied with the HEQ5 and
EQ6 Mount can be used for accurate polar alignment. This
method of polar alignment is sufficient for virtually all visual
use of the telescope.
To use the polarscope, the declination axis must be rotated
such that the hole in the shaft is in front of the polar scope.
This allows the user to see all the way through the Right
Ascension shaft. If possible, this procedure should be
carried out while the telescope and counterweights are on
the mount. This prevents the mount from becoming
misaligned when the load on the tripod is changed.
Leveling the tripod will make it easier to use the Azimuth
and Altitude adjustments on the mount when trying to
center the stars in the polar scope. The tripod can be
made level by using a bubble level or carpenter's level.
T
he P
olar
scope