9
.5
Adjust the interpupillary distance
•
This operation can be done only on binocular models.
1. Hold the right and left parts of the observation head using
both hands and adjust the interpupillary distance by turning
the two parts until one circle of light can be seen. (Fig. 12)
•
The graduation on the interpupillary distance indicator
pointed by the spot "." on the eyepiece holder, shows the
distance between the operator's eyes.
The range of the interpupillary distance is 48- 75 mm.
9.6
Diopter adjustment
•
This operation can be done only on binocular models.
1. Look into the right eyepiece with your right eye only, and fo-
cus on the specimen.
2. Look into the left eyepiece with your left eye only. If the image
is not sharp, use the diopter adjustment ring
sate. (Fig. 13)
•
The adjustment range is ±5 diopter. The number indicat-
ed on the adjustment ring graduation should correspond
to the operator's diopter correction.
9.7
Use of oil immersion objective
B-155 and B-159 models only
1. Focus the specimen with a low power objective.
2. Lower the stage.
3. Put a drop of oil (provided) on the area of the specimen to be
observed. (Fig. 14)
•
Make sure that there are no oil bubbles. Air bubbles in
the oil damage the image quality.
•
To check for bubbles: remove an eyepiece, fully open the ap-
erture diaphragm and observe the objective exit pupil. (The
pupil must be circular and bright).
•
To remove the bubbles, gently move the nosepiece to the
right and left to move the immersion objective a few times
and allow the air bubbles to move.
4. Insert immersion objective.
5. Return the stage to the upper focusing point and obtain an
optimal focus using the fine focus knob.
6. After use, gently remove the oil with a soft paper towel or a
lightly moistened optic paper with a mixture of ethyl ether
(70%) and absolute ethyl alcohol (30%).
•
The immersion oil, if not immediately cleaned, could
crystallize creating a glass-like layer.
•
In this situation the observation of the specimen would
be difficult (even not impossible) due to the presence of
an additional thickness on the objective.
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