Bresser National Geographic 90-39100 Instrucciones De Uso página 14

NOTE:
Make sure to place the microscope's table (7) in its lowest
position before changing the objective in order to prevent
damage to the microscope.
Insert the 10X eyepiece (No. 1, 1) in the Barlow lens (No. 1, 3).
Take care that the Barlow lens is inserted completely into the monocular head (No.
1, 4).
5. Observation
After you have set up the microscope with the proper illumination, the following
principles are important:
Begin each observation at the lowest magnifi cation, so that the centre and position
of the object to be viewed is in focus. The higher the magnifi cation, the more light
is required for good picture quality.
Place a permanent slide culture directly under the microscope lens on the plate (7).
The specimen to be examined must be directly over the lighting.
Look through the eyepiece (1 and 2) and carefully turn the focus wheel (8) until you
can see a sharp picture.
Now you can progress to a higher magnifi cation. Slowly pull the Barlow lens (No.
2, 3) out of the monocular barrel (No. 2, 4). When the Barlow lens is nearly entirely
pulled out, the magnifi cation is raised to 2X.
For even higher magnifi cation, you can put the 16X eyepiece (2) into the objec-
tive revolver (6) and rotate the objective revolver to a higher magnifi cation (10X or
40X).
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Depending on the preparation, higher magnifi cations do not
always lead to better pictures.
When changing the magnifi cation of your microscope by changing or adjusting the
eyepiece, objective lens or Barlow lens, you must readjust the focus wheel (8) to
sharpen the image.
NOTE:
Please be very careful when doing this. If you move the mechani-
cal plate upward too fast, the objective lens and the slide can
touch and become damaged.
6. Condition and prepare viewed objects
6.1. Condition
With the Barlow lens nearly fully extended, your microscope's magnifi cation can
be doubled. Both transparent and non-transparent specimens can be examined
with this microscope, which features both direct and transmitted light. If opaque
specimens are being examined, such as small animals, plant parts, tissues, stones
and the like, the light is refl ected from the specimen, through the lens and eye-
piece, where it is magnifi ed, to the eye (refl ected light principle, switch position
I). If opaque specimens are being examined, the light from below goes through
the specimen, lens and eyepiece to the eye and is magnifi ed en route (direct light
principle, switch position II).
Some small water organisms, plant parts and animal components are transparent
by nature, but many others require pretreatment — that is, you need to make a thin-
nest possible slice of the object by hand cutting or using a microtome, and then
examine this sample.
6.2. Creation of thin preparation cuts
Specimens should be sliced as thin as possible. A little wax or paraffi n is needed to
achieve the best results. Put the wax into a heat-safe bowl and heat it over a fl ame
until the wax is melted. You can use a candle fl ame to melt the wax.