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SNC2D
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Biology – Microscopes
The word biology means the study of life. Translated from Greek:
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Types of Microscopes
• Compound Microscopes
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• Image seen with this type of microscope is
• Is the most commonly used. You can
even living ones. It has high magnification. However, it has a low
resolution
• A dissection microscope
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• The image that appears is
• It is used for dissection to get a better
because it has a low
magnification.
Microscope Parts and Function
PART
EYEPIECE
BODY TUBE
ARM
BASE
STAGE
STAGE CLIPS
NOSEPIECE
OBJECTIVE LENS
LIGHT
IRIS
COARSE FOCUS
FINE FOCUS
FUNCTION
Handling the Microscope
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The biggest reason
microscopes break is not because they wear out, but because they are dropped.
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This leaves oil which is hard to clean
and particles which may damage the lens. If a lens needs cleaning,
, a lens cloth or a lens pen and be gentle. Do not use your shirt or a towel.
Obtain a slide and place it on the stage of the microscope. Secure the slide with
the stage clips.
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Rotate the objectives on the nosepiece of the microscope until the shortest
objective is over the slide and make sure the objective clicks into place. The
shortest objective is LOW power.
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Low power lens gives the widest field of view and makes it easier to find the
specimen when you look through the microscope. Finding the specimen at high
power, without first centering it in the field of view at low power, is nearly
impossible.
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Open the iris if your microscope has an iris or rotate the diaphragm (circular
plate under the stage with different size holes) until one of the large holes is
centered under the slide. This is your light control.
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, but once you have focused and
found your specimen in the field of view, start reducing light until you see the
most amount of detail.
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The brightest setting is typically not the best for contrast and detail
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. It is easy to focus right past the correct
focus point if you are going too fast.
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Use the
fine focus knob as needed.
power and fine tune with the
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Refocus, but slowly. You will
only be seeing a part the specimen.
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Move the slide slowly back and forth if you cannot see anything. If you get lost
and lose the specimen, go back to low power, center the slide and try again. It
may take several tries to find a specimen, but this is normal.
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If you managed medium power and have the specimen focused and in the field
of view, you can try high power.
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Once again,
and slowly and
carefully
(high power) until it
clicks into place. It will barely clear the slide, so be careful.
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The next rule is very important. DO NOT USE COARSE FOCUS ON HIGH POWER
EVER! If your microscope has both fine and coarse focus,
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Why? The objective is very close to the slide, now. If you use coarse focus, you
can jam the objective down onto the slide and break the slide. Worse, yet, you
may soil and even damage the objective.
Microscope Calculations
o To calculate the total magnification of an image that you are viewing through the
microscope take the
.
o The
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seen when looking through the eye piece.
To measure the filed of view, you will need a see through ruler or
grid.
Place the clear plastic ruler with the mm markings on the stage
and look through the low power objective. Focus your image.
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Total magnification on low
= field of view on other power
Total magnification on other power = field of view on low power
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Size of object = diameter of field of view (µm)
number of times the object fits
across the field of view
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Magnification of drawing =


size of drawing in µm
size of object in µm
Measure the size of your drawing and convert to µm
Divide by the size of the object (last slide)
Wet Mount Slide
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. If your specimen is too thick, then
the coverslip will wobble on top of the sample like a see-saw
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directly over the specimen. If you put too
much water over the specimen, then the coverslip will float on top of the water.
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at a 45 degree angle (approximately), with
one edge touching the water drop, and let go.
Staining a Slide
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As soon as the stain has covered the area containing the specimen you are
finished. The stain does not need to be under the entire coverslip. If the stain
does not cover the area needed, get a new piece of paper towel and add more
stain until it does.
Biological Drawings
• Drawings, labels, name and other information must be done
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• Use
. The drawing should be
and kept to the
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• The
of the drawing is simply the name of the object you are looking
at.
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.
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. Do not add structures because you think
they should be there. Do not shade or sketch.