Sokkia iM-50 Series Operator's Manual page 208

2. Turn the upper part through 180° and check the
position of the survey point in the reticle.
If the surveying point is still centered, no
adjustment is necessary.
If the survey point is no longer centered in the
optical plummet, perform the following adjustment.
PROCEDURE Adjusting
3. Correct half the deviation with the levelling foot
screw.
4. Remove the optical plummet reticle cover.
5. Turn the 4 adjusting screws of the optical plummet
to adjust the remaining half of the deviation using
hexagonal wrench (1.3 mm) as shown below.
When the survey point is on the lower (upper) part
of the illustration:
Loosen the upper (lower) adjusting screw slightly,
and tighten the upper (lower) adjusting screw the
same amount to move the survey point to a point
directly under the center of the optical plummet.
(It will move to the line in the figure on the right.)
If the survey point is on the solid line (dotted line):
Loosen the right (left) adjusting screw slightly and,
tighten the left (right) adjusting screw by the same
amount to move the survey point to a point in the
center of the optical plummet.
6. Check to make sure that the survey point remains
centered on the reticle even if the upper part of
the instrument is rotated.
If necessary, perform the adjustment again.
Cover
203
35. CHECKS AND ADJUSTMENTS
Adjusting screw