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15. Refocusing Stopper
The refocusing stopper on the left-hand coaxial coarse/fine focusing knob is used to
mark the position of the coarse focusing knob where a specimen is in focus.
Once the refocusing stopper is clamped at the in-focus position, refocusing is much
easier after the objective is shifted for specimen change or other purpose. All you
have to do for refocusing is rotate the coarse focusing knob until it reaches the limit.
The refocusing stopper is useful, for example, if the objective is very close to the
stage because the container of the specimen has a thick bottom plate, and the
magnification can only be changed by lowering the objective.
(1) At the position where a specimen is in focus, turn the refocusing stopper clamp
ring to clamp the stopper.
The stopper has been clamped when the black
triangle mark on the side of the clamp ring is at the upmost position.
(2) Lower the focusing mechanism by using the coarse focusing knob only, then
change the objective.
(3) Raise the focusing mechanism slowly, again by using the coarse focusing knob
only, until it reaches the limit.
Here, the microscope is roughly in focus. Then,
rotate the fine focusing knob to give a sharp focus.
When the refocusing stopper is not used, be sure to loosen the clamp until it
reaches the limit.
If clamped, the focusing mechanism cannot be moved up from
the clamped position with the coarse focusing knob.
However, stage movement
with the fine focusing knob is not affected.
Figure 4-14
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