Microscopes
I.
A.
Types of Microscopes
Light Microscopes (compound and
dissecting)
1. Advantages
a. Can look at living things
b. See in color
c. Requires simple preparation
d. Fairly inexpensive
2. Disadvantages
a. Specimens must be thin.
b. Limited magnification (~2,000X)
c. Resolution is poor on higher magnifications
 What is resolution?
 Read page 847 in your textbook, then draw and
label the picture of a compound microscope
There will be a quiz on this picture and your lab!
B.
Transmission & Scanning
Electron Microscopes
1.
Advantages
a. Greater magnification (scanning 100,000 X and
transmission 200,000 X)
b. Scanning EM will give you a 3-D view
Transmission EM
Scanning EM
2. Disadvantages
a. Can only look at dead things.
b. Specimen preparation is time consuming
and expensive.
c. Objects appear black and white.
d. Very expensive.
What type of microscope took
this picture?
What kind of microscope
took this picture?
What type of microscope was
used to take both of these
pictures?
II.
How to use the
microscope
A. Carrying the microscope
1. Always use 2 hands; one on the arm and one
on the base.
2. Don’t tilt or swing the microscope because the
eyepiece may fall out.
B. Setting up the microscope
1. Place microscope on a flat, even surface, about
3-5 inches from the edge of the table.
2. Unwrap cord and plug into the nearest outlet.
3. Use lens paper only to clean eyepiece and
objectives.
4. Use paper towels to clean slides and any nonglass parts.
5. Place the microscope slide on the stage and
secure it with the metal clips.
C. Using the microscope
1. Always begin…
a. On lowest/scanning objective (4X)
b. Eyepiece set to 10X
c. Diaphragm set to 1 or 2 (controls amount of light)
d. Nosepiece lowered all the way down
2. While looking through the eyepiece, move the
slide back and forth, or side to side until you
locate a blurry object.
3. Use the coarse adjustment knob to center and
focus on the blurry object.
4. Switch to next higher power objective; center and
focus again. Adjust light if necessary.
5. If image isn’t clear enough repeat steps 1- 4
going to the highest magnification.
 Never use coarse adjustment (large knob)
while on high power or you may break or
scratch the lens.
6. Switch back to scanning objective before you
remove slide.
D. Putting away the microscope
1. Make sure objective is set to scanning (4x)
2. Clean and dry stage, slide and cover-slip.
3. Remove the plug from the socket (don’t pull
on the cord), wrap up the cord, not too tight
or it will break out of the base of the scope.
4. Lower the eyepiece, so it’s all the way down.
Magnification and Field of View