➂
If the bubble is displaced, it should be adjusted.
When adjusting half of the bubble displacement is taken out with
the foot screws and the other half using the adjusting pin till the
bubble reaches the center of the circle. Rotate the telescope and
repeat the same procedure until the bubble stays in the center of
the circle in whatever direction the telescope is pointing.
5.2. Level line of sight
5.2.1. Testing
➀
Set and level the instrument at a point midway between two
points. Set leveling staff on point A, B. Align the staff by telescope
and note the readings of a1, b1 (See Fig. 5(1)).
a1
1/2
A
(1)
➁
Move the instrument to a position (point C) about 2m from one of
the points A or B. Level the instrument once again and note the
readings of a2, b2 (See Fig. 5(2)). If a1 - b1 is not equal to a2 -
b2, adjustment is required.
5.2.2. Adjusting
➀
At point C, screw off the back cover to expose the reticle
adjusting screw.
➁
Using the adjusting pin, carefully turn the adjusting screw until
the horizontal hair gives the reading b2 = a2 - (a1 - b1) on staff.
➂
Repeat the above procedure until the deviation is less than
2mm/30m.
➃
Screw on the back cover after completing the adjustment.
b1
a2
1/2
B
2m
A
C
(2)
b2
Fig. 5
B
UK