Anatomy 14 M. J. Malachowski, Ph.D. Name:________________________
The magnification, or power, of a lens is usually indicated by a whole number followed
by an “X”. (Sometimes the “X” is omitted.)
The total magnification of the microscope is obtained by multiplying the eyepiece power
times the power of the objective. Provide the magnification of the following.
_________ Eyepiece alone
_________ Scanning objective alone
_________ Low power objective alone
_________ High power objective alone
_________ Eyepiece and scanning objective combined
_________ Eyepiece and low power objective combined
_________ Eyepiece and high power objective combined
Note: These observed and calculated are correct only for the microscope you are currently using,
other microscopes may have different values, check each microscope before use!
II. Power Comparison
Use a letter “e” on a slide, place the slide on the stage with the letters Right-Side-Up. Center it
in the field and focus; draw it exactly as it appears in the microscope. Do for all three
magnifications, starting, always, with the lowest and working up.
Scanning Power Low Power High Power
Push the slide to the right. The image moves to the ___________ .
Push the slide up and away from you. The image moves ___________ .
If the specimen on the slide is right side up, the image will appear __________ .
III. Brightness of the field/image.
The field is the illuminated circular area you “see” when you look into a microscope. (If it is all
black, check the position of the turret/indentation.) As you increase the magnification, does the
field become brighter or darker?
IV. Sharpness of the Image
As you increase magnification, does the image appear darker or fuzzier?
V. Measuring the Field
Start in Scanning power, Take a clear plastic ruler and place it under the clips as if it were a
slide. Use the metric scale. Look through the microscope, place one black dividing line at the
extreme left edge of the field, and measure the width of the field by counting the number of
divisions visible plus estimate the distance to/from the next/last division. Repeat for low and
Scanning field ______________________ mm diameter
Low Power field ______________________ mm diameter
High Power field ______________________ mm diameter
As the magnification increases, does the field encompass a larger or smaller area? ___________
Whenever you lose sight of your specimen, you should always look for it at a lower power. Why
Note: As you increase the magnification, the image becomes larger and larger; at the same time
the field grew darker and the image became fuzzier. While it is possible to keep increasing
magnification, the resolving power of the light microscope is limited, and you obtain “empty”
magnification, extremely fuzzy images!
VI. Before putting the microscope away,
1. Remove the slide, 2. Rotate the shortest objective lens into position, 3. Lower the body tube
all the way down (giving the microscope the shortest profile).
VII. Microscope Specimens - Each drawing should have a title and a magnification:
insert on two lines under the drawing!
A. Moisten the slide by wetting your fingertip B. Swish a little saliva around in your mouth to
and rubbing the slide with it. Sprinkle five make it foamy, get a small drop of it on the tip
grains of salt on the moisture. Do not use water of your tongue, and touch the tip of your tongue
or a cover slip. Draw the salt at high power. to the center of a clean cover slip.. Drop the
slip, saliva side down, onto a clean slide.
The saliva should not contain anything visible
except air bubbles, which are what you are
looking for. Draw a small and a large bubble at
low power and remember what they look like,
You will see them again.
C Obtain one of the prepared slides of colored
silk fibers. Observe it in scanning, low, and ________________________
high power. Using high power, carefully focus
to determine which thread is on the top, middle, D. Use one of the available specimen
and bottom. When you believe you have preparations, observe and draw it at high power.
figured out the arrangement, check with the
instructor to have it signed off. Note: leave the
fiber set up under high power so the instructor
can check your work!!!!
Middle ___________________ _____________________________________
Bottom ___________________ ________________________