Centering With The Optical Plummet - Pentax ETH-302 Instruction Manual

4.4 Centering with the optical plummet

After [4.3 Leveling with the plate vials] is completed, the instrument must
be centered above the station point.
Focus the optical plummet reticule by rotating the optical plummet
1
eyepiece knob.
Focus the station point by rotating the optical plummet focusing knob.
2
Loosen the tripod center screw. Look through the optical plummet
3
eyepiece, and move the instrument bottom plate until the reticule
center coincides with the station point. (Take care not to rotate
the instrument)
Tighten the tripod center screw. Ascertain that the bubble stays
4
positioned in the center when rotating the plate vial position in steps
of 90°. If the bubble is not positioned in the center, adjust with the
leveling screws. (Refer to [4.3 Leveling with the plate vial]).
Even if the bubble is shifted by one graduation in
centering is just 0.3mm, at the instrument height of 1.4m, giving little
effect on the survey result.
Center mark
, deviation of
4
31