Calibration Zoom | 185
3 The bubbles of the instrument and tribrach levels must be centered. If one
or both circular levels are not centered, adjust as follows.
Instrument: If the bubble extends beyond the circle, use the Allen key
supplied to center it with the adjustment screws.
Tribrach: If the bubble extends beyond the circle, adjust it using the
adjustment pin in conjunction with the adjustment screws. Turn the
adjustment screws:
• To the left: and the bubble approaches the screw.
• To the right: and the bubble goes away from the screw.
4 Repeat step 3 on the instrument and tribrach until both circular levels are
centered and no further adjustments are necessary.
)
After the calibration, no adjustment screw should be loose.