MOM Ni A3
precise level MOM  Ni A3
record number: 58
instrument type: precise level
manufacturer: MOM
serial number: 994685/A
model: Ni A3
weight: 3.22 kg
dimensions (l/w/h): 26/14/21 cm
year of manufacture: 1960
instrument set up: circular level
compensator
Telescope
diameter of objective: 67 mm
magnification: 30 x, 40 x, 50 x
type: telescope with internal focusing
cross hairs/reticule: wedge crosshairs with two distance hairs, constant 100
precision: 0.2 mm/km

The precise compensating level was made in 1960. The mechanical compensator, a prism on the pendulum, ensures precise levelling of the line-of-sight axis. An optical micrometer with a plane parallel plate and a 5 mm measuring range determines the reading on the staff with a resolution of 0,05 mm.

A special feature is the three eyepiece attachments that change the magnification of the telescope, the options being 30x, 40x and 50x. Different magnifications should be used at different distances to the staff. The tests carried out as part of teaching work did not show any significant differences in the precision of the results depending on the attachment used.

The precision of this precise level, as quoted by the manufacturer, is 0.2 mm for 1 km double-run levelling, which is the same as that of the much more well-known Zeiss Ni 002 instrument. Experience with this instrument has shown that it lags behind the Ni 002 in both precision and functionality.

In 2016, the instrument was cleaned and damage to the varnish was repaired.