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11.4 Perpendicularity of Collimation axis and Cross axis (2C)
Check
1. Set target A to be about 100 meters away from the
instrument and set the vertical angle of the target to be within
±3°. Level the instrument precisely and turn on the
instrument.
2. Aim at the target A and readout the left horizontal angle.
e.g. HA L=10°13′10″
3. Screw off the vertical and horizontal locking screw and
turn around the telescope to aim at the same target A. When
aiming at it precisely, lock the vertical and horizontal locking
screw to read out the right angle. e.g. HA R=190°13′40″
4. 2C=L-(R±180°)=-30″≥±20″, then the instrument need
to be calibrated.
Calibration
1. Turn the instrument to the correct horizontal angle
which eliminates C with the help of horizontal inching screw:
R+C=190°13′40″-15″=190°13′25″
2. Unload the reticule cover in between the eyepiece and
the coarse focusing knob. Adjust the two horizontal cross wire
correction screw on the left and right by screwing off one then
screwing up the other. Shift the reticule to aim at the target A
with the cross wire center.
3. Repeat the steps above until the absolute value of 2C is
less than 10″(|2C|
<
10″)