Optical Plummet - Pentax ETH-302 Instruction Manual

6.7 Optical plummet

Inspection
Place a piece of white paper, with a cross drawn on it, directly under
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the instrument.
Look through the optical plummet, and move the paper so that the
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intersecting point of the cross comes to the center of the field of view.
Adjust the leveling screws so that the center mark of the optical
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plummet coincides with the intersection point of the cross.
Rotate the instrument around the vertical axis. Look through the
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optical plummet each step of 90° rotation, and observe the center
mark position against the intersection point of the cross.
If the center mark always coincides with the intersection point, no
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adjustment is necessary. When it does not coincide, the following
adjustments are required.
Adjustment
Remove the cover of the optical plummet.
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Mark the point set on the line of sight at each step of 90° on the
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white paper and call them A,B, C and D.
Join the opposed points (A, C and B, D) with a straight line, and set
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intersecting point 0.
Turn four optical plummet adjusting screws with the adjusting pin so
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that the center mark coincides with the intersection point 0.
Repeat procedure again to confirm.
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Optical plummet adjusting screw
Cap of optical plummet
Point
Center mark
Adjusting pin for the center mark
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