118
(3) Calculating the horizontal collimation error C according to C=
（
Hl- Hr±180°
）
/2, if
C<8
″
, no adjustment will be necessary. If C>8
″
, proceed with the following adjustment.
Ⅱ
. Adjustment
(1)
Power on the instrument after leveling-up, and rotate telescope to initial.
(2)
Aim at the cross-hairs of collimator or the obvious target at a distance. Gets
the face left angle reading H1 and the face right angle reading Hr.
(3) Rotate the instrument in face right position, turning horizontal tangent screw until
Hr
′
=Hr+C.
(4) Loosen the shield of telescope’s reticle. Adjusting two screws at left and at right until
the vertical hairs of telescope’s reticle coincides with the cross-hairs of collimator or
target.
(5) Repeat the check and adjustment procedure until the error is accepted.
NOTE:
1. When adjusting the screws of reticle, firstly loosen the screw on the moving direction
of reticle, secondly tighten another screw by the same mount, clockwise turning is for
tightening, and anticlockwise turning is for loosening, the turning mount for tightening or
loosening should be same.
2. After the reticle adjustment, it is necessary to adjust the vertical index error by program,
see “
§
23.10 Vertical Index Error”.
26.9 Tilt Sensor
If the tilt angle shown on the display shifts from tilt angle 0
°
(zero point), the instrument
is not correctly leveled. This will adversely affect angle measurement. Perform the
following procedures to cancel the tilt zero point error.
Ⅰ
. Check
Set-up the instrument on tripod or adjustment platform, and level it accurately.
