Foif J2-2, Инструкция по эксплуатации

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13
The instrument can be centred under a plumb bob suspended from a roof or ceiling
point, by lining up the tip of the plumb bob with the small point an the centre of the
optical sight. Before doing this the instrument must be leveled-up and the telescope
set horizontal.
1.2 Centring with optical plummet
For precision centring, the optical plummet is used. Turn eyepiece (18) of optical
plummet until cross hairs are in focus. Pull put the optical plummet until ground point
is in focus. Slacken tripod fixing screw and move instrument over tripod plate until
cross hairs coincide with ground mark. Turn the alidade through 180° and check
centring. Centring again and levelling again if necessary.
2.Levelling up
2.1 Levelling up with plate level
With horizontal clamp open, turn alidade so that plate level (13) is parallel to the line
joining any two footscrews A and B by equal and opposite rotations. Turn the alidade
through 90°in clockwise direction and centre the bubble with footscrew C. Repeat
the procedure until the bubble remains in the same, through not necessarily central
position, for all directions of the alidade. The plate level should be protected from