D. Changing the magnification.
1. Position the 10X objective (5) in the optical path.
2. This microscope has already been parfocalised, although it is possible that there are small
differences between the objectives. In this case, the focus should be readjusted with the fine
focus knob (18).
3. When changing between objectives 40X y 100X (optional) do so with great care, ensuring
that the objectives do not rub against the slide and damage the lens front.
4. To obtain maximum resolution with the 100X objective (optional), it is necessary to apply
immersion oil between the cover slip and the front lens of the objective.
a. Only use a tiny amount of immersion oil, a drop should be enough.
b. If air bubbles appear, they can be eliminated by rotating the nosepiece slightly,
and then repositioning it.
c. After observing, all parts that have come into contact with immersion oil must be
cleaned. Use a soft cotton cloth, lightly dampened with Xylene. If the 100X
objective is not cleaned, the oil will dry on the lens front, and block the view. This
could also damage the lens.
NB: Immersion oil must ONLY be used with the 100X objective. If it comes into
contact with any other objective, it must be cleaned immediately.
E. Critical illumination on bright field.
It is the optimum degree of illumination that perfectly proportions the group of elements used for
illumination, basically the condenser. To achieve critical illumination, an object on the illuminator
must be brought into focus.
1. Move the polarizer (11) from the illumination field.
2. In the case of the PM-1805, remove the analyser.
3. Focus on a slide with the 10X objective (5).
4. Place a flat object on the illuminator (19). The object must be one that allows light to pass
through, for example, a slide.
5. Without letting go of the slide, bring it into focus, moving the condenser (8) by turning the
collar with the other hand.
6. When critical illumination has been achieved, the slide can be removed from the illuminator.
If anything irregular appears in the field of view, an optical element of the illuminator appears
in focus for example, move the condenser slightly so it is out of focus. This should give you
the best illumination possible, and that closest to critical illumination.
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