Observation; Observation Specimen - Characteristics; Setting Up The Direct Light Table; Microscope Settings (Direct Light) - Bresser Duolux 50-12000 Manual De Instrucciones

Insert the 5x eyepiece (Fig. A 2) in the Barlow lens (Fig. A 3). Make sure
the Barlow lens is wholly inserted in the eyepiece barrel (Fig. A 4) and
does not project.

7. Observation

Once you´ve set the microscope up with the right lighting and settings
the principles below apply.
Start with simple observation at lowest magnification. Centring and
adjustment of the specimen is thus made easier. The higher the
magnification the more light is needed for good observation quality.
Place a slide with a permanent specimen right under the lens on the
microscope table and secure it in place with the clamps (Fig. A 18).
Important. The specimen must be precisely sited in the centre of the
transmitted lighting. Look through the eyepiece (Fig. A 1/2) and turn
the focussing wheel (Fig. A 8) carefully until you get it right. Use the
dimmer wheel (Fig. A 11) to set the brightness of the underlighting to
view specimen details optimally. You can then set higher magnifica-
tion by slowly pulling the Barlow lens (Fig. A 3) out of the eyepiece
barrel (Fig. A 4). When nearly fully extracted magnification is nearly
doubled.
For even higher magnification use the 16x eyepiece (Fig. A 1) and
then turn the nosepiece (Fig. A 20) to a higher setting (10x/40x).
Important note
Higher magnification need not necessarily lead to better
results. This depends on the specimen.
Please note
If magnification is changed (eyepiece or objective change,
Barlow lens extraction) the focus must be re-adjusted using
the focussing wheel (Fig. A 8). Be very cautious when doing
this. If you turn the lens down too fast you may damage it
and/or the slide.

8. Observation specimen - characteristics

and preparation
8.1 Condition
Both transparent and non-transparent specimens can be examined
with this microscope, which is a direct as well as transmitted light
model. If opaque specimens are examined - such as small animals,
plant parts, tissue, stone and so on - the light is reflected from the
specimen through the objective and eyepiece, where it is magnified,
to the eye (reflected light principle). If opaque specimens are exam-
ined the light from below goes through the specimen, objective and
eyepiece to the eye and is magnified en route (direct light principle).
Many small organisms of the water, plant parts and finest animal
components have now from nature these transparent characteristic,
other ones must be accordingly prepared. Is it that we make it by
means of a pre-treatment or penetration with suitable materials
(media) transparent or thus that we cut finest wafers off of them (hand
cut, MicroCut) and these then examine. With these methods will us the
following part make familiar.
8.2 Producing a thin specimen slide
As already stated, specimens for microscopic observation should
always be sliced as thin as possible. A little wax or paraffin is needed
to achieve the best results. A candle can be used for the purpose. The
wax is put in a bowl and heated over a flame. The specimen is then
dipped several times in the liquid wax. The wax is finally allowed to
harden. Use a MicroCut (Fig. B 25) or knife/scalpel (careful!!!) to slice
the wax-coated specimen as thinly as possible. The slices are laid on
slides and covered with a covering glass.
8.3 Making your own specimens
Place the specimen on the slide and add a drop of distilled water with
a pipette (Fig. B 27) to the specimen (Fig. B I).
Set a covering glass vertically at the edge of the drop so that the
water runs along the glass edges (Fig. B II). Then slowly place the
covering slide atop the drop.
Note: The gum media provided (Fig. B 31) is used in making
permanent slides. Add it instead of distilled water. The medi-
um hardens and the specimen is then permanently affixed
to the slide.

9. Setting up the direct light table

Pull the sliding change tray out of the table to its stop (as in Fig. A
15). Then insert the specimen plate for direkt light (Fig. A 17) in the
central table aperture.

10. Microscope settings (direct light)

The wide adjustment range of the microscope allows you to examine
specimens up to a height of about 40 mm. The variable direct lighting
can be precisely adjusted using the joystick (Fig. A 6) to the speci-
men. In examining transparent specimens the underlighting with its
approximate diameter of 32 mm is an ideal aid to getting a really good
view of the specimen. You can adjust both upper and lower lighting
individually or together to optimally illuminate any specimen.
The best results in the direct light mode are achieved by combining
the 5x eyepiece and the 4x objective. Any other combination increases
magnification but reduces the field of visibility.

11. Experiments (transmitted light)

Once you´re familiar with the microscope you can try the following
experiments and view the results.
11.1 Newspaper print
Objects:
1. A small piece of paper from a newspaper with parts of a picture
and some letters,
2. a similar piece of paper from an illustrated magazine.
Use your microscope at the lowest magnification and use the preparation
of the daily paper. The letters seen are broken out, because the news-
paper is printed on raw, inferior paper. Letters of the magazines appear
smoother and more complete. The picture of the daily paper consists
of many small points, which appear somewhat dirty. The pixels (raster
points) of the magazine appear sharply.
11.2 Textile fibers
Objects and accessories:
1. Threads of different textiles: Cotton, line, wool, silk, Celanese,
nylon etc.,
2. two needles.
Each thread is put on a glass slide and frayed with the help of the two
needles. The threads are dampened and covered with a cover glass.
The microscope is adjusted to a low magnification. Cotton fibres are
of vegetable origin and look under the microscope like a flat, turned
volume. The fibres are thicker and rounder at the edges than in the
centre. Cotton fibres consist primary of long, collapsed tubes. Linen
fibres are also of vegetable origin; they are round and run in straight
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