Nikon SC - Objective Handling and Working Distance

5. Coarse focusing
1) The coarse focus knob is to be used for
coarse focusing and for fine focusing with
the 4X objective.
2) It can also be used for lowering the stage
convenience when replacing a specimen,
removing immersion oil. etc.
3) The relation between the direction of rota¬
tion of the coarse focus knob and that of
vertical movement of the stage is as indicat¬
ed by the arrows in Fig. 20-A. B.
6 . Fine Focusing
1) The fine focus knob is to be used for fine
focusing with the 10X or higher power
objectives.
2 ) It is also used when exchanging objectives or
focusing on each successive layer of a thick
specimen,
3) The relation between the direction of rota¬
tion of the fine focus knob and that of ver¬
tical movement of the stage is the same as
for the coarse focus knob. {Fig. 20-A. B)
4) The range of the fine focus knob is 2.2mm.
The white line on the fine focus knob shows
the center of the fine focusing range. It is
necessary beforehand to position the white
line on the fine focus knob opposite the end
of the coarse focus knob. (Fig. 21)
7. Working distance of objectives
1) "Working distance" is the clearance between
the front of objective and the upper surface
of the coverglass when the image of the
specimen is in sharp focus.
In this microscope it is as follows for each
objective:
Objective Working distance
4XSC.28mm
lOXSC.8mm
40XSC.0.73mm
lOOXSC.0.16mm
2} As shown above, the working distances of
the 40x and 100X objectives are very small,
incurring the danger of pressing on the
specimen. These two objectives, therefore,
are specifically equipped with a safety de¬
vice, which permits rising of the front of
objective, at the moment it touches the
specimen.
Fig. 21
9