Microscope Study Guide - Exercise 3
Human Anatomy & Physiology I • BIOL 2111
- Know the information below.
- Be able to identify the
microscope parts on one of the lab microscopes.
- Be able to answer questions about
focusing technique as described below.
(cf. Human Anatomy & Physiology Laboratory Manual
Exercise 3 - The Microscope
pp. 21-29 in 8th Ed.
pp. 27-34 in 9th Ed.)
The microscopes we use in lab are compound light microscopes.
Compound light microscopes have lenses in the
oculars and in the objectives.
- the column between the base and the stage
It is used for carrying the microscope.
- the platform that holds a slide
- stage clips
- hold a slide in place on the stage
- stage control knobs
- knobs below the stage that can move it forward and backward or
from side to side
- coarse focus
- the large knob for focusing at
4x and 10x objective
- fine focus
- the small knob for focusing at
40x and 100x objective
- the lenses of the microscope nearest the eye
The ocular is 10x.
- the lenses of the microscope immediately above the slide
Notice that each of the 4 objectives
is labeled with its magnification and that the higher
magnifications are longer.
- 4x magnification
- is used to scan the slide and find the specimen
- 100x magnification
- used only for the
oil immersion technique where oil is placed on the microscope slide
- nosepiece or turret
- the revolving device that holds the
- light source
- an electric bulb in the microscope base
- lenses below the stage that focus light from the
light source to improve resolution
- iris diaphragm lever
- controls the brightness of light from the microscope’s
light source below the stage
that passes through the slide into the objective
- total magnification
- the power of the ocular
multiplied by the power of the objective
For instance, if the ocular is 10x
and the objective is 4x, then the
total magnification is 40x.
- field of view
- the surface area of a microscope slide that can be viewed
without moving the slide
The diameter of the field of view
decreases as magnification increases.
- depth of field
- the vertical distance that is in focus
at a particular magnification without changing the focus
Depth of field decreases as magnification increases.
At high magnifications only a very thin slice
of the specimen can be in focus at one time.
- refers to the degree of detail that can be seen through a microscope
At a higher resolution,
two objects can be closer and still be distinguished as separate.
Wavelength affects resolution.
Shorter wavelengths have higher resolution.
That's why the microscope light source uses
blue light ,
475 nm (475 x 10-9 m).
Electron microscopes have a very high resolution because
electrons have a shorter wavelength than visible light.
The wavelength of an electron is around
10 pm (10 x 10-12 m), one-thounsandth that of visible light.
- means a microscope will hold
focus when you change objectives
Focusing the microscope at 40x objective
Remember: The ocular is 10x.
- Move the 10x objective into position.
(10x ocular times 10x objective equals 100x total)
- Bring the stage up with the coarse adjustment knob until it stops.
- Slowly move the stage down with the coarse adjustment knob until the specimen is in focus.
- Leave the stage in its position!
- Move the 40x objective into position.
(10x ocular times 40x objective equals 400x total)
- Focus on the specimen with the fine adjustment knob.
Meiji Techno Co., Ltd. microscope
Meiji Techno Co., Ltd. makes the lab microscopes.
National Optical & Scientific Instruments Inc. digital microscope
National Optical & Scientific Instruments Inc.
makes the DC5-163 digital microsope that is used to take slide pictures for the computer.
It’s a very expensive piece of equipment.
Motic digital microscopy software suite
Motic Images Plus 2.0ML
is the program for capturing and processing the slide digital images from the