The eye is like a camera

The idea

Like a camera, the eye's lens system forms an inverted real image on a light-sensitive screen, the retina; light enters through the cornea, where most refraction occurs, and the crystalline lens finely adjusts the focal length.

Seeing a picture

A camera has a lens that makes a picture on a screen inside the camera. Your eye also has a lens.

Where does the picture of the world form inside your eye?

• On a light-sensitive screen at the back, the retina
• On the thin bulge at the front of the eye
• Inside the lens itself

Follow the light

Press Next step to follow the light.

A natural camera

The eye works like a camera. The cornea does most of the bending of the light. The crystalline lens only adjusts the focus a little, so that things near and far can be sharp on the retina. The picture on the retina is upside down.

Like a camera, the eye's lens system forms an inverted real image on a light-sensitive screen, the retina. Light enters through the cornea, where most refraction occurs, and the crystalline lens provides the finer adjustment of focal length.

Notes

The eye is like a camera: the cornea (most refraction) and the crystalline lens (finer adjustment) form an inverted real image on the retina.

Check yourself

On which part of the eye is the image formed?

Where does most of the refraction of light entering the eye occur?

The image formed on the retina is…

What is the job of the crystalline lens?

• The cornea. The cornea is the thin transparent bulge where light enters the eye. The image is formed on the retina.
• The retina — correct. Yes!
• The pupil. The pupil is the opening that regulates the amount of light entering the eye. The image is formed on the retina.
• In the crystalline lens. The crystalline lens merely provides the finer adjustment of focal length. Most refraction occurs at the cornea.
• On the retina. The retina is the light-sensitive screen on which the image forms. Most refraction occurs at the cornea.
• At the outer surface of the cornea — correct. Yes!
• real and inverted — correct. Yes!
• virtual and erect. The eye lens forms an inverted real image on the retina.
• real and erect. The real image on the retina is inverted, not erect.
• To do most of the bending of the light. Most of the bending occurs at the cornea. The crystalline lens only makes finer adjustments.
• To adjust the focal length finely so that objects at different distances are focused on the retina — correct. Yes!
• To carry signals to the brain. The optic nerves carry the electrical signals to the brain.