13_english, Perating the eq2 mount, Sing the optional barlow lens – Sky-Watcher EQ2 MOUNT User Manual
Page 13

O
perating the EQ2 mount
0
10
20
30
40
50
60
70
80
90
13
Dec. fine
adjustment
R.A. fine
adjustment
R.A. scale
Dec. lock knob
Dec. scale
The EQ2 mount has controls for both conventional altitude
(up-down) and azimuth (left-right) directions of motion. These
two adjustments are suggested for large direction changes and
for terrestrial viewing. Use the large knurled knob located
underneath for azimuth adjustments. Loosen the knob and
rotate the mount head around the azimuth axis. Use the altitude
adjustment T-bolts for altitude adjustments (Fig.e).
In addition, this mount has Right Ascension (hour angle) and
declination direction controls for polar-aligned astronomical
observing. Loosen the lock knobs to make large direction
changes. Use the control cables for fine adjustment after the lock
knobs have both been locked (Fig.e1). An additional scale is
included for the altitude axis. This allows polar alignment for
your local latitude. (Fig.d2)
Altitude adjustment
(up-down)
Azimuth adjustment
(left-right)
Dec. fine adjustment
R.A. fine adjustment
R.A. scale
Dec. lock knob
R.A. lock knob
Dec. scale
Fig.f
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 catadioptric (Fig.f). 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 eyepiece in your collection.
Barlow
Eyepiece
(Reflecting Telescopes)
Barlow
Diagonal
Eyepiece
(Refracting and
Maksutov Telescopes)
Fig.d1
Fig.d2
Fig.e1
Fig.e