Fig. 46
Fig. 45
1
2
N.A. scale
Aperture iris
diaphragm image
Objective pupil
70-80%
30-20%
Aperture Iris Diaphragm (Figs. 45 & 46)
} The aperture iris diaphragm determines the numerical aperture of the
illumination system. It has an effect of adjusting the balance between
image resolution and contrast. Stopping down the aperture iris diaphragm
increases the depth of focus.
· To observe an optimum image, set the condenser aperture iris diaphragm
to between 70 and 80% of the NA @ (Numerical Aperture) of the objective
in use.
· Align the index on the aperture iris diaphragm ring 2 with the NA scale
value between 70% and 80% of the NA @ of the objective (Fig. 45).
At this time, if you remove an eyepiece and look into the observation tube,
you will be able to see the objective pupil and aperture iris diaphragm
image as shown in Fig. 46.
2 Compatibility of Objectives and Condensers
Objective
Magnification
Condenser
Achromat/aplanat
U-AAC
Swing-out
U-SC3
Motorized universal
BX3-UCD8A
1.25X
Applicable by moving top lens
out of the light path.
Applicable when U-CO1.25X is
combined.
2X
Applicable by moving top lens
out of the light path.
4X
10-60X
Applicable Engage top lens in light path. Engage top lens in light path.
100X
* When using the U-SC3 swing-out condenser together with a 1.25X to 4X objective, fully open the condenser aperture
iris diaphragm and use the field iris diaphragm in the base as aperture diaphragm. With the 1.25X to 2X objectives, the
surroundings of the field of view may become dark.
} To obtain better illumination in camera recording using a 1.25X to 4X objective, use of the U-ULC-2 for ultralow magnification
is recommended.
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