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,
.
USE OF THE ACCESSORIES
EYEPIECE
Place the eyepiece in position by pushing it into
the eyepiece
sliding
sleeve.
To focus, turn the
slow
motion focusing knobs.
Engraved on the
cap is a letter and number symbol.
The letiers
H or
HM stand
for
Huygenian,
or
Huygenian
Mittenzwey, while the numbers represent the focal
length
of
the
eyepiece expressed in millimeters.
The magnifying power of the telescope
can
be
obtained
by dividing
the
focal
length
(Fo)
of
the
objec
ti
ve
lens by
the
focal
length
(Fe) of the eye
piece.
Thus, if
the
focal length
o.f
the
objec
ti
ve
lens is 910mm and that
of
the eyepiece is 125mm,
the magnifying power is 910 divided by 125; or
73X
.
Observers who wear other than astigmatic eye
glasses should, if possible, remove them before
viewing
.
BARLOW LENS
The use of the Barlow lens doubles the magnify·
ing power of the telescope.
To install this
lens,
slide
it into the eyepiece sliding sleeve
to the
cen
ter
of
the
sleeve; then
slide
the eyepiece into
the Barlow lens tube.
STAR DIAGONAL PRISM
This device is an
L shaped
tube containing a
right
angle reflecting prism.
It
passes all
the
light
and makes a comfortable position possible
when
viewing
stars at a high altitude.
In
se
rt the
prism
in place
of
the eyepiece and slip the eyepiece
into the prism sleeve (Figure
11).
When the prism
Figure
11
is used,
the
draw tube must be pushed in about
60mm
to
provide a proper lig·ht path.
With the
prism installed, the image is erect but the right
and left
sides
are reversed.
SUN GLASS
The
sun
glass intercepts the heat and glare of
the sun's rays and permits safe, direct solar ob
servation.
In use,
it is screwed into the end of
the eyepiece.
FINDER TELESCOPE
The
small,
6X,
finder telescope is mounted by
fixed supports on
the large
telescope
tube
and
is parallel to it.
Its
objective
lens has a focal
length
of
30mm in clear aperture and is equipped
with cross wires on
the
field of
view.
Both the
eyepiece and
the
objective lens can be focused
separately.
First, bring the object into view by
means of the eyepiece and
cente
r
it on
' the:
··bos~
wires;
then,
using the objective lens, bring the
object into sharp focus.
It is difficult to locate an object when high
powers
'
are used because of the small field of
view.
The
function of the finder
telesc
ope
is to find an object
through the use of
.
its wide field of view which
allows
the
scanning of a much greater area
of
the skey from any position. Once the desired ob
jec
t
is located in
the
center
of
the
cross
wires
of
the finder telescope, it should
automatically
be in the
cen
ter
of the field of
view
of
the
main
telesc
ope.
If
thi
s
does not prove
to
be
so,.
per·
form this simple
check:
In
the daytime, use a distant weather
vane,
rod,
or
other similar object and at night use a bright
star upon which
to
focus and center the finder
telescope. Cross check the images in both instru
ments
to
see if
they
are centered, 'using a low
power eyepiece in
the
main
telesc
ope.
If the
images are not both centered, adjust the direc
tion of the finder telescope by means of the ad
justing
screws so as
to
align the axes of both
the
finder and the main telescope. Replace
the
low power eyepiece with
the
desired high power
eyepiece and perfect
the
adjustment.
ERECTlNiG PRISM
Since an astronomical
telescope
shows
an inverted
image, an erecting prism is needed for terrestrial
purposes.
The
erect image
is
obtained by using
two right angle pr
rs
ms.
·
An ordinary astronomical
eyepiece is used instead of an erecting eyepiece.
This markes possible a wide field of
view
and less
loss of light. When erecting prism is used,
the
draw
tube
must
be
shortened
approximately
100mm
.
SUN PROJECTING SCREEN
The image
o
f
the sun is projected through the
telescope
onto a screen. Assemble the sun screen
as shown (Figure 12). When attaching the
ring
figure
12
of the rod holding
the
screen to
the
draw
tube,
.
be sure
that the
grooved
side
of
the
ring
is
directed toward the
tube. For best resu
l
ts, use
a paper clip
to
fasten a sheet of
white
paper to
the reflecting side of the screen. Use
the
H20mm
eyepiece for projection. The
image
obtained
will
be
10cm
in diameter. To
ob
tain
an upright
image
on the screen, use the diagonal prism.
To get
a magnified view of of sun spots, use a higher
powered eyepiece.
7
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