2-8
2 PREPARATION FOR MEASUREMENT
2.5 Setting Instrument Up for Measurement
Mount the instrument to the tripod. Level and center the instrument precisely to insure the best
performance. Use tripods with a tripod screw of 5/8 in. diameter and 11 threads per inch, such as the
Type E TOPCON wide- frame wooden tripod.
•
Mount the battery in the instrument before performing this operation because the instrument will tilt
slightly if the battery is mounted after levelling.
2.5.1 Centering
PROCEDURE: Centering with the optical plummet eyepiece
1
Make sure the legs are spaced at equal intervals and
the head is approximately level.
Set the tripod so that the head is positioned over the
survey point.
Make sure the tripod shoes are firmly fixed in the
ground.
2
Place the instrument on the tripod head.
Supporting it with one hand, tighten the centering screw
on the bottom of the unit to make sure it is secured to
the tripod.
3
Looking through the optical plummet eyepiece, turn the
optical plummet eyepiece to focus on the reticle.
Turn the optical plummet focussing ring to focus on the
survey point.
4
Adjust the levelling foot screws to center the survey
point in the optical plummet reticle.
5
Continue to the levelling procedure.
See Section 2.5.2 “Levelling”.
Centering
screw
Focussing on the survey point
Focussing
on the
reticle
