Microscopy

How a compound microscope works, part by part.

A compound microscope forms an image with two lens systems in series. The objective produces a magnified real image inside the tube; the eyepiece magnifies that image again for the eye. Total magnification is the product of the two, so a 40× objective with a 10× eyepiece gives 400×.

The most-used page in this series is the labelled diagram: compound microscope parts labeled, with the function of each part set out in a table.

Magnification is the easy part. What decides whether a specimen is actually visible is resolution — the smallest separation at which two points stay distinct — and contrast, whether the specimen differs enough from its background to be seen at all. Most of the equipment below exists to manage those two, not magnification.