SKY-WATCHER MINI DOB 76 User manual

INSTRUCTION MANUAL
MINI DOB 76
190309V2

PARTS DIAGRAM
ASSEMBLY
Finderscope
Eyepiece
Focusing Wheel
Alt-Azimuth Base
Fig.a
Fig.b
1. Remove the telescope and
accessories from the package.
Locate finderscope optical assembly.
Remove the two knurled thumbscrews
near the opening of the telescope
main tube.
Position the finderscope bracket over
the screws in the telescope main body.
Secure the finderscope bracket with
the two knurled thumbscrews. (Fig.a)
2.
3.
4. Locate the eyepiece. Loosen the eyepiece
lock screws and slide the eyepiece into the
holder. Slightly tighten the screws to hold the
eyepiece in place. Do not over-tighten the
screws. (Fig.b)
1

2
OPERATING YOUR TELESCOPE
Fig.d
Focusing
Slowly turn the focus wheel (Fig.d),
one way or the other, until the image in
the eyepiece is sharp. 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
haven't yet reached outside
temperature. Refocusing is almost
always necessary when you change
an eyepiece or add or remove a
Barlow lens.
Positioning the telescope
To position the telescope to the
desired angle, simply move the
telescope tube up and down in
altitude or swivel the telescope
around the base in azimuth. (Fig.c)
Fig.e
Fig.c
Aligning the finderscope
These fixed magnification scopes
mounted on the optical tube are very
useful accessories. When they are
correctly aligned with the telescope,
objects can be quickly located and
brought to the centre of the field.
Alignment is best done outdoors in day
light when it's easier to locate objects.
If it is necessary to refocus your
finderscope, sight on an object that is
at least 500 yards (metres) away. Twist
the end of the finderscope until focus is
reached (Fig.e).
NEVER USE YOUR DOB TO
LOOK DIRECTLY AT THE SUN.
PERMANENT EYE DAMAGE
WILL RESULT.

3
Calculating the Magnification (Power)
magnification = = = 80X
Focal length of the telescope
Focal length of the eyepiece
800mm
10mm
The magnification produced by a telescope is determined by the focal length
of the eyepiece that is used with it. To determine a magnification for your
telescope, divide its focal length by the focal length of the eyepieces you are
going to use. For example, a 10mm focal length eyepiece will give 80X
magnification with an 800mm focal length telescope.
When you are looking at astronomical objects, you are looking through a
column of air that reaches to the edge of space and that column seldom stays
still. Similarly, when viewing over land you are often looking through heat
waves radiating from the ground, house, buildings, etc. Your telescope may
be able to give very high magnification but what you end up magnifying is all
the turbulence between the telescope and the subject. A good rule of thumb
is that the usable magnification of a telescope is about 2X per mm of aperture
under good conditions.
Cleaning your telescope
Replace the dust cap over end of telescope whenever not in use. This
prevents dust from settling on mirror or lens surface. Do not clean mirror or
lens unless you are familiar with optical surfaces. Clean finderscope and
eyepieces with special lens paper only. Eyepieces should be handled with
care, avoid touching optical surfaces.
Fig.f
Choose a distant object that is at
least 500 yards away and point the
main telescope at the object. Adjust
the telescope so that the object is in
the centre of the view in your
eyepiece.
Check the finderscope to see if the
object centred in the main telescope
view is centred on the crosshairs.
Use the three alignment screws to
centre the finderscope crosshairs
on the object (Fig.f).
1.
2.
3.