ASTRONZ DOBSONIAN GS680 Manuale utente
OWNER’S MANUAL
DOBSONIAN TELESCOPE
ASTRONZ GS680 200mm ( 8”) F/6
ASTRONZ GS880 254mm (10”) F/5
ASTRONZ GS980 303mm (12”) F/5
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Astronz (Astronomy NZ Ltd) is fully owned by the Auckland
Astronomical Society and operated by its members.
Our mission is to supply quality telescopes and accessories
at a reasonable price. By importing and selling direct from
the manufacturer to the customer we can keep our prices
down and give you the best value on the New Zealand
market.
As passionate astronomers ourselves, we understand how
important it is to have the highest quality, precision optics.
Our speciality is in easy to use instruments that can be
used for real astronomy, and not outgrown in a matter of
months.
Astronz supports astronomy throughout New Zealand and
continues to invest its prots back into the astronomical
community nationwide.
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Contents
Introduction 4
Specication 5
Parts 6
Assembly 7
Using your Telescope 10
Focuser 10
Eyepieces 10
Finderscope 11
Observation Tips 12
Selecting a SIte 12
Cooling 12
Seeing 12
Storage 13
Maintainence 13
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Thank you for purchasing an Astronz Dobsonian
telescope. This precision optical instrument is built
with the highest quality materials and with proper
care will provide many years of reliable service.
The Dobsonian telescope is an “alt-azimuth” (up-down/
left-right) mounted Newtonian reector type telescope.
The design was popularised in the 1960’s by San Francisco
astronomer John Dobson, who famously made telescopes
from recycled “junk” such as cardboard tubes and scrap
wood, and was largely responsible for making large aperture
telescopes available to amateur astronomers for a reasonable
cost.
In a Newtonian reector telescope, invented by British scientist Sir
Issac Newton (1642-1727), light enters the telescope throught the top
of the telescope (the open end) and is reected o a concave parabolic
curved mirror at the bottom of the tube. The light is then reected o a at
mirror mounted at an angle of 45 degrees, into an eypiece on the side of the
telescope tube.
Introduction
⚠ WARNING
DO NOT use the telescope or nderscope to look at the sun with-
out an approved solar lter. Doing so will cause permanent dam-
age and even blindness.
NEVER use a solar lter that attaches to the eyepiece. Only
approved solar lters that completely cover the opening of the
optical tube will provide adequate protection.
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Finderscope
Focuser
Focus Adjustment
Altitude Bearing
Azimuth Bearing
Optical Tube Assembly
(OTA)
Dobsonian Base
Cooling Fan
Collimation Screws
GS680
Focal Length: 1200mm
Focal Ratio: f/6
Aperture: 200mm
Weight: Telescope 13kg
Base 10kg
Length: Telescope 1.25m
Magnication: 9mm EP 133x
30mm EP 40x
GS880
Focal Length: 1250mm
Focal Ratio: f/5
Aperture: 254mm
Weight: Telescope 18kg
Base 12kg
Length: Telescope 1.35m
Magnication: 9mm EP 139x
30mm EP 42x
GS980
Focal Length: 1500mm
Focal Ratio: f/5
Aperture: 303mm
Weight: Telescope 22kg
Base 14kg
Length: Telescope 1.45m
Magnication: 9mm EP 167x
30mm EP 50x
Specications
Telescope: Newtonian Reector Optical Tube Assembly.
Mirror: BK7 glass, parabolic, with mirror surface quality over 1/16 wave RMS. Cooling fan.
Mount: Dobsonian base with brake / tension system. Roller bearings for smooth movement.
Focuser: 2” Dual Speed 10:1 Crayford Focuser. 1.25” to 2” Adapter.
Supplied Accessories:
9mm Plossl 1.25” Eyepiece
30mm Superview 2” Eyepiece
2” Extension Tube
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Unbox all parts for the base assembly and identify all the parts below:
A. Base Sides (2) F. Handle (and screws)
B. Base Front G. Feet (and screws) (3)
C. Upper Base Plates H. Long Screws (10)
D Lower Base Plate I. Eyepiece Tray (and screws)
E. Bearing Plates (3) J. Adjustment Bolt (wih large and small washers,
ball bearing and bushing)
A B C D
E F G
H I J
Base Assembly
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Step 1: Screw the handle (F)
to the Base Front (B) using the
provided screws into the pre-
drilled holes.
Step 2: Screw the two Base
Sides (A) to the Base Front
(B) using the Long Screws (H)
Ensure the sides are rmly at-
tached, but do not overtighten.
Step 3: Flip the assembled
sides upside down and secure
to the Upper Base Plate (C) us-
ing Long Screws (H) (note: the
Upper Base Plate has a center
hole and six predrilled holes.
Ensure that the recessed holes
are facing away from the hous-
ing so screw heads can be ush)
Step 4: Attach feet (G) to the Lower Base
Plate (D) (note: this is the one with the brass
insert in the centre and three pre-drilled holes
for the feet.)
Step 5: Flip the Lower Base Plate over onto
its feet and insert the metal bushing (sleeve)
from the Adjustment Bolt into the centre hole
Step 6: Place the Bearing Plates (E) onto the
bushing ensurung they are kept in the correct
order (the plate with the metal roller bearings
sandwiched between the other two plates
Step 7: The whole assembly from Step 3 should now also be carefully lifted onto the bushing, and
should rotate freely
Step 8: Assemble the Adjustement Bolt (J) in the following order: Bolt -Small Washer - Ball Bear-
ing - Large Washer and insert into the bushing to secure all the base plate parts together
Step 9: The nal step is to install the Eyepiece Tray (I) to
the side of the base assembly with the scres provided.
Your Dobsonian base is now completed. The adjustment knob on the base controls how easy it is
to move the base (and telescope) in the Azimuth (left/right) direction.
A
A
B
C
D
E
F
G
G
H
HH
J
I
8
Locate the two Altitude bearings and install onto the sides of the
optical tube using the screws already tted in the slots on each side
of the optical tube and hex wrench provided.
The graduated scale allows you to make adjustments to balance
the optical tube (particuarly if you use any heavy accessories). Nor-
mally these should be in the centre, taking care that the bearings on
each side should be adjusted the same.
The “U-Shaped” blocks on the bearings are designed to t perfectly
into the “U-shaped” cutouts on the dosonian base. The knobs on
the altitude bearings can be used to adjust how easy it is to move
the telescope in the altitude (up/down) direction
Telescope Assembly
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Locate the nder scope and the rubber O-ring, position the O-ring in the groove on the nder
scope body.
Loosen the thumbscrew
on the “dovetail” nder
scope base on the optical
tube, and install the nd-
erscope bracket, tighten-
ing the screw to hold it in
place.
Loosen the two plastic
adjusting screws on the
nder scope base and
slide the nder scope, eye-
piece rst, into the bracket
until the O-ring seats.
Your Dobsonian telescope
is now fully asembled and
ready for nder alignment
and observing
Finderscope Assembly
10
Focuser
Your telescope is equipped with a high quality Crayford type focuser that can take both 1.25 inch
and 2 inch eyepieces.
1.25 inch eyepieces are tted by loosening the
thumbscrew on the 1.25 - 2-inch adapter (A)
and installing the metal barrel of the eyepiece
into the hole (after removing all plastic dust
caps. Tighten to thumbscrew to secure the
eyepiece (do not overtighten)
To use 2 inch eypieces, loosen the thumb-
screw on the focuser (B), remove the 1.25 -
2-inch adapter and install the 2-inch eyepiece
as above but in the larger 2-inch diameter
opening.
Adjust the Tension Screw (E) so that the
eypiece/focuser moves smoothly in and out
when the focus knob (C) is turned. The Lock
Screw (F) will prevent the eypiece focussing
(ie turning the focus knobs (C & D) will not
move the focuser).
In operation, the sliver focus knob (C) will
allow you to roughly focus the eypiece, whilst the black knob (D) moves more slowly and will allow
ne focus (approximately 10:1 ratio).
Eyepieces
Your telescope is supplied with two high quality eyepieces; a 1.25” 9mm Plossl and a 2” 30mm
Superview wide angle eypiece. Calculating the magnication of an eyepiece is simple and uses
the following formula:
Power (or Magnication) = Focal length of telescope
Focal length of eyepiece
So for an Astronz 200mm Dobsonian: 1200mm/9mm = 133 and 1200mm/30mm = 40
The basic rule of thumb to remember is that an eyepiece with a larger number has a lower power
and will show a greater area of sky. When using your telescope you will generally start o using
the lowest power eyepiece you have and switching to a higher power if required only once you
have located the object you are interested in.
A
B
C
D
F E
Using Your Telescope
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