(5) The focusing knob (3) is used to focus the telescope. The telescope eyepiece (1) is provided
with a diopter scale, enabling individual focusing preferences. Through the eyepiece for the tubular
level (16), which magnifies approximately 2 1/2 times, two half images of the level bubble may be
observed (as shown in Figure 4-3). A reflector provides illumination. One side bears a mirror, while the
other side is lacquered white. The reflector can be turned using the reflector knob (2) to achieve the best
possible reflection. The micrometer scale receives its illumination from the same reflector, so if the
level is well lighted, good illumination is automatically assured. The interval lines of the scale stand out
sharply against a light background and are usually well defined.
Figure 4-3. Tubular Coincident Level Bubble and Fine-Adjustment Screw
(6) The circular level (18) is situated beneath the reflector. In cases where it is advantageous to
erect the instrument in as high a position as possible, the level can be observed in the mirror, entirely
free from any parallax.
(7) Four adjusting screws are inserted on the objective side of the level, which can be used to
adjust the tubular level. To allow for an easy field adjustment, the protective glass in front of the
objective is cut in the form of a wedge. After loosening the locking screw (10), the protective glass rim
may be turned, permitting the line of sight to be set horizontally (following the centering of the level