The Ni 2 level with an astronomical measuring attachment was produced by Zeiss Oberkochen in 1951. The Ni 2 is a legend, as it is the world's first compensating level. The compensator, the main part of which is an optical prism on a pendulum, represents a major technological advantage in levels. Measurements are significantly faster and precision is higher.

The level is built in a modular design. Without accessories, it is a medium-precision level with 2.5 mm for 1 km double-run levelling. It can be used in combination with an optical micrometer with plane parallel plate. With the correct crosshairs design, it becomes a precise level, its precision being 0.5 mm for 1 km double-run levelling. As in our example, a special prism for astronomical observations can be added to the instrument, which can then be used as an astrolabe. We observe the stars at a constant angle and measure the time of their passage through the lines of the crosshairs. This allows us to determine the coordinates of the observation site. The instrument requires illumination for such night-time observations.

The instrument is in the same condition as when it was originally taken out of service. The lamp holder for the illumination of the crosshairs is missing.