This is a dissecting or stereo microscope.
It has only two sets of lenses, including the eyepiece.
The specimen to be observed is an opaque object (light does not pass through it).
The observer sees the surface of the specimen being studied.
The specimen is placed in a container on the stage of the microscope.
The compound microscope
We use the compound microscope to observe microscopic specimens:
It has more than two sets of lenses.
It has an eyepiece lens (or ocular) and two or more sets of objective lenses (this microscope has four lenses) on a nosepiece that usually revolves.
This kind of microscope is also called a light microscope as it requires a source of light to pass through the specimen.
The specimen observed with this kind of microscope is usually microscopic and has to be translucent (allows light to pass through it).
The specimen to be observed is placed on the stage of this microscope.
Parts of the microscope
- eyepiece or ocular
2. body tube
3. fine adjustment knob
5. high power objective
6. low power objective
8. mirror (many microscopes have a light instead)
10. coarse adjustment
12. stage clip
13. inclination joint
- eyepiece (ocular) – where you look through to see the image
- body tube – Holds the eyepiece and connects it down to the objectives
- fine adjustment knob – Moves the body of the microscope up/down more slowly; gives very fine control. Lets you get the specimen approximately focused. Always used after we first use the coarse adjustment knob.
- nosepiece-the rotating piece at the bottom of the body tube which lets us choose between several different additional lenses (objectives.)
- high power objective — used for high power magnification of the specimen (the longer objective lens)
- low power objective — used for low power magnification of the specimen
- diaphragm – controls the amount of light going through to the specimen
- light or mirror – source of light usually found near the base of the microscope; makes the specimen easier to see
- base – supports the microscope
- coarse adjustment knob — Moves the body of the microscope up/down more quickly; lets you get the specimen approximately focused. It’s all that you need when using the low power lens,
- arm – Holds the main part of the microscope to the base.
- stage clips -shiny metal clips which hold the slide in place.
- inclination joint -is used to tilt the microscope
- Always carry the microscope with two hands – one on the arm and one underneath the base of the microscope. Hold it up so that it does not hit other objects.
- Do not touch the lenses. If they are dirty, ask the teacher for special lens paper.
- If using a microscope with a mirror, do not use direct sunlight as the light source. Blindness can result. If using a microscope with a light, turn off light when not in use.
- Notify teacher if a slide or cover slip breaks. Do not handle broken glass.
- Always clean slides and microscope when finished. Store microscope set on the lowest power objective with the nosepiece turned down to its lowest position (using the coarse adjustment knob). Cover microscope with dust cover and return it to storage as directed by your teacher.
How to use
- Always begin focusing on the lowest possible power. Center the specimen you are observing in the field of view before switching to a higher power.
- Move the objectives away from the specimen when focusing – so their is no collision between the objective being used and the slide/cover slip which may damage the objective lens.
- As you switch from low to high power, the field of view becomes darker.
To deal with this the diaphragm needs to be opened to allow in more light. (Frequently on low power the diaphragm needs to be partially closed as it is too bright.)
- As you switch from low to high power the field of view becomes smaller.
Images viewed under the light microscope are reversed (backward) and inverted (upside down).
Inquiry, Experimentation, and Design in the Classroom
SIS2. Design and conduct scientific investigations. Properly use instruments, equipment, and materials (e.g., scales, probeware, meter sticks, microscopes, computers) including set-up, calibration (if required), technique, maintenance, and storage.