Niemals mit dem Teleskop in oder in die Nähe der Sonne blicken:
E
rblindungsgEfahr
!
16
16
MAINTENANCE
IMPORTANT NOTE:
You should only carry out the maintenance procedure described below by
yourself if you are already familiar with this technical procedure, as even
smallest errors during the adjustment can cause damage to the device!
The manufacturer accepts no liability for damage resulting from improper
handling or maintenance!
We recommend that untrained users and users with little previous know-
ledge consult our service department before carrying out an adjustment
(for more information, see the chapter "Warranty and Service"). Any main-
tenance/service that may be required is subject to a charge.
Adjustment of the Newton system
All Newtonian telescopes are precisely collimated at the factory before
shipment. However, it may happen that the optical system is misaligned
due to vibrations during transport and has to be re-collimated. However,
readjusting the optics is quite simple.
However, performing collimation on an NT 150/750 telescope is a little dif-
ferent from other Newtonian reflector telescopes due to the fast focal ratio
of f/5 of the primary mirror. Let's look at the image of a typical Newtonian
reflector telescope. When the observer looks through the telescope (without
eyepiece), the eye of the observer, the secondary mirror, primary mirror and
eyepiece extension appear relatively exactly centered in the middle. (see
figure 7). On the other hand, with a "fast" focal ratio ( f/5 or f/4 or smaller )
of a Newtonian telescope, the secondary mirror must be offset in two direc-
tions from the centre: 1. away from the focuser and 2. towards the main
mirror (by the same amount). This so-called "offset" is a few mm in both
directions. Remember that these settings were made at the factory before
the telescope was shipped. We mention it here only so you can check that
the optics have not been badly misaligned. For fine adjustment, please fol-
low step 4 of the description below.
Fig. 31a is showing the view through a correctly collimated Newtonian
telescope as seen through a focuser without eyepiece.
For checking and possibly new optical collimation, please proceed as
follows:
1. Look through the focuser and rotate the tube in the tube clamps so
that the telescope's primary mirror is on your right and the telescope's
secondary mirror is on your left. The secondary mirror, as already shown
(2, Fig. 31a), appears in the middle. If the secondary mirror is not in the
middle, it must be centred by using the 3 adjustment screws and the
central retaining screw for the secondary mirror height adjustment which
is located in the plastic housing of the secondary mirror.
2. If the reflection of the primary mirror (3, Fig.31a) is not centered on the
surface of the secondary mirror, first center it with the 3 adjustment
b d
e f g
Eyepiece extension (profile)
Secondary mirror
d
Reflection of the primary mirror
e
Reflection of the secondary
mirror
f
Reflection of the observer’s eye
g
Retaining clips of the primary
mirror
Fig. 31a
