Download 4X 40X

Setting up a trinocular compound
microscope for best viewing
1
“Trinocular” means three oculars, or
eyepieces
Ocular tube for
mounting a
camera
Oculars for
viewing by
eye
2
“Compound” means having multiple
objective (lower) lenses mounted on
a rotating turret (lens holder)
Rotating turret
to hold
objective
lenses
Objective
lenses
3
Focusing the microscope on specimen slides can be
accomplished with a coarse adjustment control for rapid
adjustment, and a fine control for small adjustments, particularly
necessary at high magnification
levels.
Coarse control
Fine control
4
The “mechanical stage” holds specimen slides and
allows them to be moved precisely under objective
lenses to focus on any area of interest.
5
The microscope illuminator, or light source, provides
light for transmission through the specimen for viewing
its structure. The amount of light is modified with a
shutter or diaphragm using a
control knob to open or close it
for more or less light.
Diaphragm control
Illuminator
6
The condenser focuses light from the illuminator onto the
specimen slide to provide the best lighting for viewing. It can be
raised or lowered and centered for precise focusing as necessary.
It has its own shutter diaphragm too,
for varying the amount of light
reaching the specimen slide.
Centering
controls
Diaphragm
control
Focusing
knobs
7
To send light from the
microscope to a camera
mounted on the third ocular
tube, a diverter-prism is moved
into the field of view by pulling
out its control arm.
8
Setting up a microscope for best
viewing involves adjusting the parts of
the scope to the viewer, focusing the
scope on the specimen slide and
adjusting the illuminator or light source
to the slide being viewed.
9
Turn on microscope illuminator by rotating dimmer knob
slowly clockwise. Fast turn-on shortens bulb life.
Dimmer knob
10
Place a sample slide on the microscope
stage under the lowest power objective lens.
11
Adjust the microscope eyepieces so you can comfortably
see a well-focused image through both
Space eyepieces so you can comfortably see
through both at the same time.
If one eyepiece tube is fixed focus, close the
opposite eye and, using the microscope focusing
knob, carefully focus an image of the sample for the
open eye. (If both eyepiece tubes are variable focus,
either one will do.) Now close the other eye and use
the variable focus eyepiece tube to bring the image
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into focus for the open eye.
Focus on the specimen slide (e.g. these wood cells from a
piece of paper). Using the 4X objective lens, there will be a
much larger field of view but much less detail visible than
with the 40X lens.
4X
40X
13
Rotate the illuminator diaphragm control until the
diaphragm is closed all the way. Using the focusing
knob on the condenser, bring the diaphragm image into
as sharp focus as possible. Using the centering
controls, be sure the diaphragm image is positioned in
the center of the field of view.
4X
40X
14
Adjust the condenser diaphragm so that the specimen
features are as clearly visible as desired.
Condenser diaphragm
wide open
Condenser diaphragm closed
down to provide correct
contrast for clear viewing
15
The nature of light and lenses results in a plane of focus which
becomes thinner as magnification increases. That means for a
particular specimen slide, it becomes possible to focus through
the thickness of a specimen.
Some parts will be in focus
while others will not, as in these
wood cells focused at different
“depths” through the slide.
16
As with any images used for diagnoses, relative size
is extremely important. Whenever possible, a
comparative scale should be included with an image,
or at least the approximate magnification indicated.
cm.
approx. 100X
17
When the microscope has been adjusted to
produce the best image of a specimen, it is
ready for capturing with the camera. Now the
diverter-prism must be pulled into position to
direct light up the third ocular tube to the
camera mounted on it.
REMEMBER
What you see in the camera or on the imagecapture viewer is what will be saved to a digital
file. NOT NECESSARILY what you see by eye
through the eyepieces. BE SURE a final focus is
made in the camera viewer or on the image18
capture viewer.
REVIEW
1)Turn on microscope illuminator slowly.
2) Place specimen slide on mechanical stage
3) Focus on specimen at desired magnification
4) Adjust eyepieces for best viewing
5) Adjust condenser for best lighting
6) Adjust condenser diaphragm for best contrast
7) Refine focus for depth of field
8) Refine focus for image capture
9) Capture image
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