75
Setting phase contrast with
condensers 0.53 S23 and 0.90 S1
Phase contrast observation is possible with
condenser 0.53 S23 with objective magnifica-
tions from 5x to 100x, with condenser 0.90 S1
from 10x to 100x.
For both condensers, phase contrast is set as
described as for the 0.30 S70 condenser.
However, before the centration process itself,
correct Koehler illumination must be set.
Possible errors
Specimen: too thick, too thin, staining too
intense; refractive index of mounting medium
and specimen identical, so there is no phase
jump.
Specimen slide too thick, so Koehler illumination
not possible.
Wedge-shaped coverglass position, so centra-
tion of light and phase ring is no longer effective.
Wrong light ring, or light ring has been put in the
disc upside down.
Aperture diaphragm not open.
Light ring not centred.
Wrong light ring.
