Optika Italy B-510 Serie Manuel D'instructions page 45

11. Condenser for Brightfield/Darkfield/Phase Contrast (B-510PH)
Universal condenser provided with B-510PH allows observation in brightfield, darkfield and phase contrast.
Observation mode
Phase contrast 10x
Phase contrast 20x
Phase contrast 40x
Phase contrast 100x
11.1 Brightfield Observation (BF)
1. Rotate the condenser turret to insert the "BF" position.
2. Now repeat the steps described in the procedure "Brightfield observation procedures".
11.2 Darkfield Observation (DF)
1. Rotate the condenser turret to insert the "DF" position.
• By inserting the darkfield ring, the aperture diaphragm
opens automatically. This is a desired effect and should
not be considered a defect.
2. Insert 10x objective.
3. Place a specimen on the stage and focus.
4. Observing into eyepieces raise the condenser until a
homogeneous illumination of the specimen can be achieved,
thus obtaining a proper darkfield effect. (Fig. 78)
• Darkfield observation
be positioned higher than the position used for the
brightfield. This is not a defect.
• Darkfield requires a huge amount of light. Switching
from darkfield to brightfield, one could be dazzled. Do
not keep your eyes on the eyepieces when moving the
condenser turret from DF to BF.
• "Dry" darkfield observation, that is, without the use of
oil, is only possible with objectives having N.A. lower
than 0.7.
F F ig. 75 ig. 75
Brightfield
Darkfield
requires the condenser
F ig. 73 F ig. 73
F F ig. 76 ig. 76
to
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Condenser Turret position
BF (Fig. 73)
DF (Fig. 74)
10/20 (Fig.75)
10/20 (Fig. 75)
40 (Fig. 76)
100 (Fig. 77)
Wrong height
F F ig. 74 ig. 74
F F ig. 77 ig. 77
Correct height
F ig. 78 F ig. 78