David White L6-20, Руководство пользователя

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Exact Degree Reading
The point at which 0 on the vernier scale
touches the circle . If the 0 coincides
exactly with a degree line on the circle,
your reading will be in exact degrees.
There are no fractions of degrees, or
minutes, to be added to the reading. The
horizontal circle reading is 75°.
Fraction (Minutes) Reading
If the 0 on the vernier does not coincide
exactly with a degree line, your degree
reading is the line which the 0 has just
passed, reading up the degree scale, plus
a fraction of the next degree.
To determine the fraction, or minutes:
- Start at 0 on the vernier and read up
the vernier scale (in the same direction
as you’re reading the degree scale) until
you find a minute line that coincides
exactly with a degree line.
- 75° was the last degree line passed on
the circle.
Reading to the right on the vernier
scale, the minute line which coincides
exactly with a degree line is 45’
(Reading is 75° 45’).
Remember, each line on the vernier scale
represents 5’, so you will be reading 5’,
10’, etc. The circle degree scale is being
read to the left.
When reading the circle degree scale to
the left, read up the vernier scale in the
same direction.
Sighting and Focusing the
Telescope
Avoid touching the tripod while sighting.
- Aim the telescope 1 at the object and
sight first through the notch on the top
of the telescope for preliminary sighting.
Look through the telescope eyepiece
2
and bring the object into focus using
the focusing knob 3 .
- Rotate the instrument until the
crosshairs are positioned on or near
the target. Tighten the horizontal clamp
7 and make final settings with the
tangent fine tuning knob 8 to bring the
crosshairs exactly on point.
When sighting through the telescope,
keep both eyes open.
You will find that
this eliminates squinting, will not tire your
eyes and gives the best view through the
telescope.
Remember to avoid touching the tripod
while sighting.
Removing the instrument from
the tripod
Loosen two adjacent leveling screws
and unscrew the tripod mounting stud
while holding onto the instrument.
Remove the instrument from the tripod
and secure it in its protective carrying
case. Loosen the vertical clamp and
close the lock lever on the level-transit.
Center the telescope in the case.