Leica DM3 XL, Инструкция по эксплуатации

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8. Operation
8.7 Aperture Diaphragm
The aperture diaphragm defines the resolution,
depth of field and contrast of the microscopic
image. The best resolution is obtained when the
apertures of the objective and the condenser are
roughly the same.
When the aperture diaphragm is stopped down
to be smaller than the objective aperture, resolv-
ing power is reduced, but the contrast is en-
hanced. A noticeable reduction in the resolving
power is observed when the aperture diaphragm
is stopped down to less than 0.6x of the objective
aperture and should be avoided where possible.
In polarization microscopy, stopping down the
aperture diaphragm generally results in more in-
tense colors.
The aperture diaphragm is set according to the
viewer’s subjective impression of the image, the
scale on the dial just serves to allow reproduc-
ible settings and does not represent absolute ap-
erture values.
Incident Light:
Color-coded Aperture Diaphragm Adjustment
The aperture diaphragm is set to the color mark
that matches the colored ring of the objective
(Fig. 24.1, Fig. 24.2).
For fluorescence and darkfield, the aperture dia-
phragm is (at first) completely open.
Caution:
The aperture diaphragm in the illumination light
path is not for setting the image brightness. Only
the rotary brightness adjustment knob or the
neutral density filter should be used for this.
An aperture diaphragm in the objective is nor-
mally fully opened. The reduction in image bright-
ness caused by stopping down results in:
Greater depth of field
Less cover glass sensitivity
Suitability for darkfield
Change in contrast
Fig. 24 Color-coded Aperture Diaphragm Adjustment
1 Adjusting the aperture diaphragm to match the colored
ring on the objective
2 Color coding
1
2