Adjustment Of Field Diaphragm - Nikon ECLIPSE Si Instructions Manual

3.9

Adjustment of field diaphragm

"Adjusting the field diaphragm" means narrowing the
illumination to limit the field of observation of the specimen.
To resize the field diaphragm, turn the field diaphragm dial.
Usually, observation is performed with the field diaphragm
narrowed until it roughly circumscribes the edge of the field
of view.
Note that the field diaphragm cannot be narrowed to inside
field of view when using a 60x or higher magnification
objective.
Optimum size of the field diaphragm
Usually, the optimum size is when the field
diaphragm roughly circumscribes the edge of the
field of view.
If the field diaphragm is opened too wide, causing
an unnecessarily wide field of illumination, stray
light enters from the outside, resulting in flares and
reducing the contrast of the optical image.
This also causes the specimen's discoloration field
to become too wide.
Adjustment of field diaphragm
Each time you change the objective, adjust the
field diaphragm.
Chapter 3 Detailed Explanation
91
Adjustment of field diaphragm
Field
diaphragm dial