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7 CHECK AND ADJUSTMENT
7.3.4 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) Loosen the vertical motion clamp only, and 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 and
tighten the vertical motion clamp.
6) Loosen the horizontal motion clamp and rotate the
instrument 180° or 200G around the vertical axis.
Fix a sight on Point A once more and tighten the
horizontal motion clamp.
7) Loosen the vertical motion clamp only and rotate
the telescope 180°
or 200g around the horizontal axis once more and
fix a sight on Point C, which should coincide with
previous Point 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 telescope 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
operation once more.
If Points B and C coincide, further adjustment is
not required. Otherwise , repeat the adjustment.
First, loosen the capstan adjustment screw on the side to which the vertical cross-hair
line must be moved. Then tighten the adjustment screw on the opposite side by an
equal amount which will leave the tension of the adjustment screws unchanged.
Revolve in the counterclockwise direction to loosen and in the clockwise direction to
tighten, but revolve as little as possible.
Perform following adjustment after complete above adjustment.
Section 7.5 “Compensation Systematic Error of Instrument”.
Section 7.2 “Checking the Optical Axis”.
Eyepiece
Telescope
Capstan
adjustment
screws
Eyepiece
Capstan
adjustment
screws
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