Foif J2-2, Инструкция по эксплуатации

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2. Horizontal Collimation Error
Ideally the line of sight should be perpendicular to the tilting axis. Any deviation
from the right angle is known as the horizontal collimation error C.
To determine horizontal collimation error:
Level up the instrument. Put instrument in face left with vertical hair sight a well
defined target. Read the horizontal circle L, transit to face right, sight target with
vertical hair. Take the reading R. Take the mean as the correct value without the
influence of horizontal collimation error, thus L – R – 180°= 2C. For angle
measurement with J2-2 theodolite, 2C of less 12
″
is usually acceptable.
To adjust:
The vertical hair is still on the target with the instrument in face left. Turn the
micrometer knob and set the correct value against the index of the micrometer scale.
Now turn the horizontal drive until the graduation lines giving the full correct value
are in exact coincidence, the reading is now correct but the vertical hair will be no
longer on the target. There are four screws by the eyepiece, the adjustment is
carried out by means of the two horizontal screws. If the vertical hair is left of the
target, unscrew the adjustment screw on the left side of the eyepiece by a small
amount and immediately screw in the right on by the same amount (if the hairs is of