Chapter 4 Microscopy (Detailed Procedure)
60
* The next procedure 10 is for the microscopes with field diaphragms. If the microscope does not
have a field diaphragm, skip to procedure 11.
10
Field Diaphragm Adjustment
(for microscopes with the field
diaphragm)
The field diaphragm is used to control the
specimen’s illuminated area relative to the
microscope’s viewfield. If it is opened to a larger
aperture than necessary, extraneous light will enter
the viewfield, which may reduce the image
contrast. Every time you change the objective
magnifications, rotate the field diaphragm ring until
the diaphragm just leaves the viewfield.
• The figures around the field diaphragm show the
approximate positions for field diaphragm ring
corresponding to each objective magnification
when 10x eyepieces are used.
• For 100x objectives, the field diaphragm cannot
be closed enough.
Replacing a Specimen Using the
Refocusing Mechanism
Try focusing on the specimen with 40x or higher magnification objective. You will find the
specimen is brought very near to the objective.
*1
It will be very difficult to change the specimen
without moving the focus knob. In a case like this, use the refocusing mechanism for easy
specimen replacement.
(1) Use one hand to gently press down
the stage.
*2
(2) While holding the stage at that position,
change the specimen.
(3) Gradually release the stage so that it rises
slowly. The stage will return to the focal
position.
*1： The distance between the front of the objective and the specimen when the specimen is in focus is
called the “working distance” of the objective. For details, see p. 74.
*2： When lowering the stage, take great care not to hit the field lens with the condenser and the parts
under the condenser
Corresponding
objective
magnification
Make sure not to
hit the field lens.
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