11
?
Return to the original position in step A. Rotate the
instrument 180°. The plate vial is mounted correctly and the
instrument is leveled nicely if the bubble is centered no
matter the instrument is rotated in any direction.
?
Please pay attention to the relations between the turning
direction of the level screws and the moving direction of
the bubble. Adjust plate vial if the bubble is not centered in
step 4.
e. Centering the instrument using the optical plummet
Adjust the eyepiece according to the observer’
s eyesight, then move
the instrument by loosening center screw until the image of the sign
on the ground centered in the circle of the reticule. Move the
instrument carefully in case it appears incline.
f.
Final leveling of the instrument
Level the instrument precisely in the similar way to step ? . Rotate
the instrument to see if the bubble in the plate vial is centered, then
tighten the center screw.