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11. Trouble Shooting
Problem
Brightfield
The specimen can not be brought into focus.
Darkfield
No definite DF contrast is possible.
The image is unevenly or not uniformly illumi-
nated.
Undesirable stray light.
Cause/Remedy
Use the correct immersion medium.
Lay the specimen with the cover glass toward
the top.
Make sure that the cover glass thickness is
correct and that it suits the indication on the ob-
jective.
Be sure that a DF objective is being used.
The objective aperture setting is too high
(maximum 0.75/1.10). If necessary, reduce the ob-
jective aperture using the iris diaphragm on the
objective.
Check the condenser centering.
Open the aperture diaphragm completely.
The magnification is too weak.
Use a higher magnification.
Incident light: Open and center the aperture
diaphragm.
Clean the specimen and neighboring lenses
(
→
p. 40).
