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8. POSSIBLE DERANGEMENTS
AND METHODS OF THEIR
ELIMINATION
When manufacturing the telescope at the plant, the optical pieces
are carefully set (adjusted), relative to each other. However, in case of
transportation or considerable impacts of the telescope the optical pieces
may be displaced (the adjustment is disturbed). In this case it is required
to readjust the telescope. Prior to this operation one should remove
the eyepiece from the eyepiece tube and check whether the mirrors are
displaced from the given places. For this purpose it is necessary to look
through the eyepiece tube from which the eyepiece and the Barlow lens
are removed. If the telescope is adjusted, the plane diagonal mirror must
be concentric relative to the brim of the focusing mount. Tile reflection of
the primary mirror in the diagonal one must be concentric as well. The
reflection of the diagonal mirror with the spider system is seen in the
primary mirror. The image of the diagonal mirror must be positioned
precisely in the middle of the primary one.
The reflection of an observer’s eye (fig. ) must be seen at the centre
of the diagonal mirror reflection.
In adjustment it is required to correct the position of the diagonal
mirror or primary one. If the image of the primary mirror in the diagonal
one is non-concentric it is necessary to change the position of the diagonal
mirror. For this purpose one unscrews screw 2 of the cell of the diagonal
mirror (fig. 4) and, operating with one of crews , brings the reflection
of the primary mirror in the diagonal one to the centre of the diagonlal
mirror.
If the position of the primary mirror is disturbed, the ref lection of the
diagonal mirror with the spider in it is seen not at the centre. In this
case one unscrews screws 2 of the cell of the primary mirror and,
by operating with three screws (fig. 3), sets the primary mirror so that
the reflection of the diagonal mirror in it is found at the centre (becomes
concentric). After setting the mirror in the correct position, one fixes
the cell in position by means of screws 2.
