The Pinhole Camera

A pinhole camera is a simple version of a camera, which does not have a lens. It is a light proof box with a small hole (the size of a pin tip) on one side and a screen on the other side. A Pinhole camera works in a similar way to the eye.

In the diagram above, you can see that the light rays hit the screen at the back then the image is projected onto the screen. As the image can be projected onto the screen, it is called a real image. This projected image is different from a mirror image, which we call a virtual image.

Like the eye, the image formed on the screen is upside down. However, our eye’s retina sends this information to the brain. Which is where the image is turned the right way up, so we can see it correctly. In a simple pinhole camera, the image formed will be upside down.

There are many similarities between the pinhole camera and the eye. The pinhole acts like the pupil, the hole at the centre of the iris that lets light through, forming an upside-down image. However, an eye has a much more complex structure. The convex lens is right behind the pupil, It is able to get thinner or thicker, which means that we can see far away objects and up close objects.

The convex lens bulges out at both sides, which helps with focusing light on the focal point, which is the retina.