9 CHECK AND ADJUSTMENT
9-7
9.3.4 Collimation of the Instrument
Collimation is required to make the line of sight of the telescope perpendicular to the horizontal axis of
the instrument, otherwise, it will not be possible to extend a straight line by direct means.
• Check
1) Set the instrument up with clear sights of
about 50 to 60meters (160 to 200 ft.) on
both sides of the instrument.
2) Level the instrument properly with the
plate level.
3) Sight Point A at approximately 50 meters
(160 ft.) distance.
4) Rotate the telescope 180° or 200g
around the horizontal axis, so that the
telescope is pointed in the opposite
direction.
5) Sight Point B, at equal distance as Point A.
6) Rotate the instrument 180° or 200g
around the vertical axis. Fix a sight on
Point A once more.
7) Rotate the telescope 180° or 200g around
the horizontal axis once more and fix a
sight on Point C, which should coincide
with previous Poi nt B.
8) If Points B and C do not coincide, adjust
in the following manner.
• Adjustment
1) Unscrew the cross-hair adjustment
section cover.
2) Find Point D at a point between Points C
and B, which should be equal to 1/4th the
distance between Points B and C and
measured from Point C. This is because
the apparent error between Points B and C
is four times the actual error since the tele-
scope has been reversed twice during the
checking operation.
3) Shift the vertical cross-hair line and
coincide it with Point D, by revolving the
left and right capstan adjustment screws
with the adjusting pin. Upon completing
the adjustment, repeat the checking opera-
tion once more.
If Points B and C coincide, further adjust-
ment is not required. Otherwise, repeat the
adjustment.
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