Focussing And Target Sighting - Sokkia DT5 Operating Manual

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The following steps are different for the DT5 and DT5S:
DT5:
9) Check the position of the surveying point in
the optical plummet eyepiece. If necessary,
loosen the centring screw slightly and care-
fully slide the instrument over the tripod head
until the surveying point is exactly centred in
the reticle.
Re-tighten the centring screw.
10) Repeat procedures 6) - 9) until the instru-
ment is correctly levelled and centred over
the surveying point.
DT5S:
9) Turn the tribrach shifting clamp
counterclockwise.
Adjust the instrument position on the tribrach
to centre the surveying point in the reticle.
Tighten the shifting clamp to fix the instru-
ment in the centred position.
Note: The DT5S shifting tribrach can be ad-
justed up to :: 10mm without moving the
base plate.
8.2 Focussing and target sighting
1) Look through the telescope at a bright,
featureless background and turn the eye-
piece clockwise, then counter-clockwise un-
til just before the reticle (cross lines) image
goes out of focus. Using this procedure,
frequent reticle re-focussing is not neces-
sary, since your eye is focussed at infinity.
EB
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IMPORTANT:
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2) Loosen the vertical and horizontal clamps
and use the peep sight ~ to bring the target
into the field of view.
Re-tighten both clamps.
3) Turn the focussing ring ~ to focus on the
target. Use the \!ertical and horizontal fine
motion screws fj, fZ to sight the target
precisely. The last adjustment of each fine
motion screw should be in a clockwise
direction.
4) While looking at the target, move your head slightly up and
down and to the right and left. If the reticle line appears to move
with respect to the target, parallax is present, which will
introduce reading errors. To eliminate this parallax effect,
re-focus with the focussing ring. (If parallax is still present,
check the reticle focussing in 1).
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5) Position of the target in relation to the reticle
lines;
a) When observing horizontal and vertical
angles at the same time.
b) When observing horizontal angle only.
c) When observing vertical angle only.
Note: Observe to the same point of the reticle
when the telescope face is changed.
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