9
STEINDORFF
®
7.
Obtaining proper Kohler illumination
With the 4x objective engaged and the specimen brought into focus, turn the field iris
diaphragm ring clockwise to close the field diaphragm to near its minimum size. The field
diaphragm is then visible (even if not in focus) (See Figure A).
Turn the sub-stage condenser focusing knob to adjust the height of the condenser to bring
the field iris diaphragm image into focus, i.e., the EDGE of the polygon (i.e. field
diaphragm image) should be as clearly in focus as possible. (See Figure B)
Using the sub-stage condenser centering screws to center the octagon of light, i.e., the field
iris diaphragm image is centered in the eyepiece field of view. (See Figure C)
To check centration, open the field iris diaphragm until its image touches the perimeter of
the field of view. If the image is not precisely inscribed in the field of view, center again.
For actual observation, open the field diaphragm until its image is slightly larger than the
field of view (i.e., the dark area is just out of view) (See Figure D)
Carefully adjust the sub-stage condenser iris diaphragm, learn to adjust the contrast to
optimize your image without introducing artifacts and without losing detail.
The whole point to adjust diopter for reticule eyepiece is to put both reticule and the specimen into focus.
To achieve this, you should first adjust the
diopter ring
to focus reticule, and then adjust the
focus knob
to focus the specimen through reticule eyepiece. After the reticule side eyepiece is ready, adjust the other
side by only turning the
diopter ring
. Pay attention to which part should be adjusted in each step. This
procedure is suitable for both eyepieces are diopter adjustable microscopes.
Aperture adjustment and proper focusing of the condenser are of critical importance in realizing the full
potential of the objective. Condenser height is controlled by a rack and pinion gear system (i.e., the
condenser focusing knob) that allows the condenser focus to be adjusted for proper illumination of the
specimen. Correct positioning of the condenser with relation to the cone of illumination and focus on the
specimen is critical to quantitative microscopy and optimum photomicrography.
Figure A Figure B Figure C Figure D Figure E
2/3
