Microscope Basics: Magnification, Field of View, and Handling

Formula for total magnification?

Ocular × Objective

What is the magnification of ocular lenses usually?

10X

If ocular is 10X and objective is 40X, total magnification is?

400X

1 mm equals how many micrometers (µm)?

1000 µm

Convert 4 mm into micrometers.

4000 µm

Convert 7500 µm into millimeters.

7.5 mm

What is field of view?

The diameter of the visible circle

If field of view is 4 mm and 8 cells fit across, average cell size is?

0.5 mm

If field of view is 2000 µm and 10 cells fit across, average cell size is?

200 µm

Which objective has the smallest working distance?

40X

How does working distance change with magnification?

Higher magnification = smaller working distance

How does depth of focus change with magnification?

Higher magnification = lower depth of focus

What is the function of the stage?

Holds the slide

Function of stage clips?

Hold the slide in place

Function of iris diaphragm?

Adjust light

Function of coarse focus knob?

Large adjustments at low power

Function of fine focus knob?

Precise focusing

Function of revolving nosepiece?

Rotates objectives

Proper storage of microscope includes?

Cover the microscope

What should always be done when switching to higher power?

Center specimen & use fine focus