How to Use a Microscope

With the light microscope you can see things such as cells that are beyond the limits of resolution of the human eye. In order to be successful in your academic persuits in biology, it is important to gain an appreciation of the microscopic world. Learning how to set up a microscope correctly is critical to achieve this success. In addition to assist you in gaining proficiency in microscopy, this learning module has a component designed to assist you with scientific illustration and drawing to scale.

Different types of light microscopes and dissecting microscopes are used in the School's teaching labs.

The microscope is expensive and should be handled with care.

How to set up for the "OLYMPUS CH-2" Microscope

Set the light intensity to about 7.

Focus the slide. Put a slide on the microscope and, using the 10 X objective, focus the image looking down the microscope using the focus control knobs (located on either side of the microscope).
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Focus the condenser using your left hand. To do this, place the corner of a piece of paper over the place near the base of the 'scope, ie where the light comes out of the microscope. The condenser should be not very far (about 3 mm) from the specimen stage.
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Adjust the sub-stage iris diaphragm. Do this by removing one of the eye-pieces (oculars) and adjusting the iris diaphragm to 3/4 open.
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repeat steps 2 and 3 EVERY time you change objectives (magnification).

Drawing a Map Diagram and Recording Scale

You probably will not have time today to start to draw sections, however it is important that you start to practice as soon as possible, so if time is available you should have a go. The requirements are shown in Appendix 1a.1. Biological drawings must have a scale so that the observer can interpret it (i.e. relate size of drawing to actual size of section).

Estimating size of the specimen:

Either: obtain an estimate of the diameter of the field of view for a particular microscope and combination of objective lens and ocular lens and estimate the proportion of the field of view that the specimen occupies.
Or: Count how many eye-piece divisions the specimen is, and using the conversion factors in the table below (noting the objective magnification) calculate the size of the specimen.
For your microscopes, with 10X oculars:

Using objective	Diameter of field of view equals	10 Eye-piece divisions equals
4 X	4.5 mm	250 µm
10 X	1.83 mm	100 µm
40 X	0.45 mm	25 µm

Click on the labels around the microscope to view explanations for each part.

If you have trouble viewing the above interactive Flash presentation or you would like to print the above information, you can view the explanation of different parts of the microscope in printable format.