16
Fig.7
2. Adjusting the rack stop.
40X and 100X(optional) objectives use a retractable security system to
avoid damage to the specimen slide or to the front of the lens, should the
two come into contact. Additionally, as a security measure, the
microscope includes a rack stop screw that regulates the upward
movement of the stage. The rack stop screw comes pre-adjusted by the
factory for standard slides with a 0.17mm thick cover slip. However, for
observing other types of slides or for using polarising equipment
(optional), adjustment may be necessary.
a. Loosen the rack stop screw (Fig. 3) with the 2mm key.
b. With the fine focus adjustment at mid-range, focus on specimen slide,
using
only
the
coarse
focus
knob,
firstly with the 4X objective, then
with
the
10X.
c. Rotate the rack stop screw until tight enough to prevent the stage
rising
further.
