A compound microscope has two lenses. The lens that a person looks into is called the ocular lens and the lens nearest the specimen (pictured) is called the objective lens. Each lens in a compound microscope serves an important purpose, and together they allow scientists to examine a specimen with much more clarity than they could with a single lens.

Here is a quick description of each of the two compound microscope lenses.

The Ocular Lens

The ocular and objective lenses offer different levels of magnification and typically the ocular lens offers less magnification than the lens closer to the specimen. On most compound microscopes the ocular lens offers either 10x or 15x levels of magnification.

The Objective Lens

The objective lens of a compound microscope (sometimes referred to as a light or optical microscope) typically offers a significantly higher level of magnification. Usually this lens offers users anywhere from 40x to 100x magnification.

Why Do Compound Microscopes Use Two Lenses?

The advantage of using two convex lenses when viewing a specimen is that the objective and ocular lenses work together to enlarge an image more than a single lens could. An additional advantage to using two lenses (and why compound microscopes are so popular) is that they place the enlarged image farther away from the human eye. This makes the image easier to view and examine.

‍