Looking at or near the Sun will cause instant and irreversible damage to your eye!
17
MAINTENANCE AND SERVICE
Alignment (Collimation) of the
Newtonian Optical System
All Bresser Newtonian telescopes are precisely collimated at the factory
before packing and shipment, and it is probable that you will not need to
make any optical adjustments before making observations. However, if the
telescope sustained rough handling in shipment, you may need to re-
collimate the optical system. Such re-collimation is not a difficult procedure
in any case.
The collimation procedure for the Meade Schmidt-Newtonians is slightly
different from that of other Newtonian reflecting telescopes, because of the
"fast" f/5 focal ratio of the primary mirror. In typical Newtonian reflectors with
more conventional focal ratios (i.e. longer focal ratios), when the observer
looks down the focuser tube (without an eyepiece in the focuser), the
images of the diagonal mirror, primary mirror, focuser tube, and the
observer's eye appear centered relative to each other. However, with the
short focal ratio primary mirror of the Newtonian, correct collimation requires
that the diagonal mirror be offset in 2 directions: (1) away from the focuser
and (2) towards the primary mirror, in equal amounts. This offset is
approximately 1/8" in each direction. Note that these offsets have been per-
formed at the factory prior to shipment of your telescope. It is only neces-
sary for you to confirm that the telescope has not been badly jarred out of
collimation, and to perform the final fine-tuning of Step 4, below.
Fig. 31a shows a correctly collimated Schmidt-Newtonian telescope, as it
appears when viewed through the focuser with the eyepiece removed.
To check and, if necessary, set the optical collimation, follow these steps:
1. Observe through the focuser and orient your body so that the telesco-
pe's primary mirror is to your right, and the correcting plate end of the
telescope tube is to your left. The diagonal mirror will appear centered
as shown (2, Fig. 31a). If the diagonal appears off center, then adjust the
4 collimation screws on the plastic diagonal mirror housing.
2. If the reflection of the primary mirror (3, Fig. 31a) is not centered on the
surface of the diagonal mirror, adjust the 4 collimation screws on the
plastic diagonal mirror housing to center the reflection. As described
above, the 4 collimation screws (Fig. 31b) on the plastic diagonal mirror
housing are used for two different adjustments during the collimation
procedure.
Note:
The R-(refractor) models do not need
any collimation
b c d e f g
b
Focuser drawtube
c
Secondary mirror
d
Reflection of primary mirror
e
Reflection of secondary mirror
f
Reflection of observer’s eye
g
Primary mirror clips
Fig. 31a
