Optika Italy B-380 Serie Manuel D'instructions page 23

11. Use of universal condenser for Brightfield/Darkfield/Phase Contrast
Universal condenser provided with B-382PH-ALC, B-383PH, B-382PHI-ALC, B-383PHI 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)
Rotate the condenser turret to insert the "BF" position. Now repeat the steps described in "Brightfield transmitted light
observation procedures" at page 18.
11.2 Darkfield observation (DF)
1. Rotate the condenser turret to insert the "DF" position.
2. Open the aperture diaphragm.
3. Place a specimen on the stage and focus.
4. Observing into eyepieces raise or lower the condenser until a homogeneous illumination of the specimen can be
achieved, thus obtaining a proper darkfield effect.
• 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 with N.A. lower than
0,7.
• Observing in darkfield, it may be necessary to raise the condenser from the normal position to obtain a more
homogeneous illumination. This is not a defect.
F F ig. 25 ig. 25
Brightfield
Darkfield
F ig. 23 F ig. 23
F F ig. 26 ig. 26
Page 23
F F ig. 24 ig. 24
Condenser Turret position
BF (Fig. 23)
DF (Fig. 24)
10/20 (Fig. 25
10/20 (Fig. 25)
40 (Fig. 26)
100 (Fig. 27)
F F ig. 27 ig. 27