Eye Distance And Dioptre Adjustment; Aperture Diaphragm - kruss MBL2000 Series Operating Manual

3. Operating the microscope / 3.1 Eye distance and dioptre adjustment / 3.2 Coarse adjustment

3.1 Eye distance and dioptre adjustment

1. Take the eyepiece carriage of the right and left
eyepiece support with both hands and adjust the
proper eye distance
2. The eye distance is correctly adjusted when the
field of vision is in focus with the eyes relaxed.
3. Take note of your eye distance shown on the scale.
4. Now turn the longitudinal tube equalizer ring of the
right eyepiece support to the value indicated on the
eye distance scale.
5. Look through the right eyepiece and focus the
object with the fine adjustment knob.
6. Now look through the left eyepiece and adjust the
tube equalizer ring without touching the coarse or
fine adjustment knob until the sample is in focus.
All transmitted light microscopes have a mechanical
tube length of 160 mm.
3.2 Coarse adjustment The coarse adjustment can be adjusted to run smooth
or rough by turning the knurled set ring between the
microscope stand and the right-hand coarse adjustment
knob. This prevents the sliding of the microscope stage
and any associated focusing errors.
Important note
Never counter-rotate the right and left adjustment
knobs at the same time.
A possible contact between the sample and the object
lens can be prevented by the pre-selection stop which
also makes the coarse focusing easier. After focusing
with the coarse adjustment knob, the lever is turned in a
clockwise direction up to the stop position.
The microscope stage can then no longer be moved
beyond this position with the coarse adjustment knob.
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3. Operating the microscope / 3.3 Aperture diaphragm / 3.4 Oil immersion lenses
Even after the stage is moved to change the object
lens, it can only be moved to the pre-selected position
with the coarse adjustment knob provided that the fine
adjustment knob has not been re-adjusted.
The sample is therefore back in focus. The adjustment
knob is not affected by the pre-selection stop.
Please note!
When adjusting with the coarse adjustment knob,
you have to ensure that the pre-selection stop is
adjusted to that particular object lens.
Otherwise, it is possible that during the simultaneous
adjustment and viewing through the eyepiece, the
object lens is moved into the sample damaging the
object lens as well as the sample.

3.3 Aperture diaphragm

The aperture diaphragm integrated in the condenser
is used to adjust the depth of sharpness of the image
contrast and the resolution power of the microscope
Pupil
lenses. In order to achieve a perfect image quality, the
diaphragm opening should generally be open 70-80%
of the object lens aperture. You can correctly adjust the
aperture diaphragm by removing the eyepiece. You can
control the image of the aperture diaphragm by the
light path (you might have to dim the light intensity).
Theoretically, the aperture diaphragm must be read-
justed after each change of the object lens.
Aperture diaphragm
2/3 of pupil diameter
3.4 Oil immersion lenses, marked with "HI" – homogeneous immersion
To make full use of the numeric aperture of an immer-
sion lens, the object lens and sample – in special cases
also the condenser – must be submerged in immersion
oil.
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