Pinhole Camera - A Camera Without Lens

What is a Pinhole Camera?

A pinhole camera is an elementary camera without a lens, however, with a small aperture, a light-proof box with a tiny hole in one side. Light from an object passes through the aperture and projects an inverted image on the opposite side of the box, known as the camera obscura effect. 

The Arab scholar Ibn al-Haytham was the first person to show how we see, for which he devised the camera obscura, the predecessor to the pinhole camera. He demonstrated how light can project an image onto a flat surface.

The first photograph was being captured with a pinhole camera by Scottish scientist Sir David Brewster in 1850.

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The above image shows a clear picture of the pinhole camera.

Pinhole Camera Materials

The materials required to make a pinhole camera include:

  1. Aluminium foil

  2. Tape

  3. Pin or a paper clip

  4. Two pieces of a white cardstock

Principle of Pinhole Camera

The pinhole camera, also known as camera obscura (which in Latin means dark room), works on one principle discussed below: 

  • The image formed by the camera shows the rectilinear propagation of light, which means the pinhole cameras rely on the fact that light travels in a straight line.

  •  When we open the shutter or a window, light illuminates to form an image on photographic paper or film placed at the back of the camera.

How to Make Pinhole Camera?

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Construction of a pinhole camera includes the steps discussed below:

  • Cut a square hole

  • Cut a hole of square shape in the center of one piece of white cardstock.

  • Tape foil over the hole

  • Cut the square-shaped aluminium foil and tape it on the hole of the cardstock.

  •  Dig a hole in the foil

  • Use a paper clip or a pin to prod a hole in the aluminium foil.

  • Now let’s experiment our work:

  • Place the second piece of cardstock on the ground and hold the piece with   aluminum foil above it (foil facing up).

  • Stand with the sun behind you and view the projected image on the card stock below. 

  • The farther you hold your camera, the bigger your projected image will be.

  • To make your projection more outlined, try placing the bottom piece of cardstock in a shadowy area while you hold the other piece in the sunlight.For exploring your creativity, you may try stabbing multiple holes in the foil, making distinct shapes, patterns and other designs. Each hole you create will turn into its own projection of the eclipse, displaying different effects. 

Pinhole Camera Model

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  1. The pinhole model is the plain camera model used in computer vision. The name originates from the concept of a pinhole camera

  2. It contains a closed box into which we make a tiny hole with a pin or a paper clip, through which light enters and strikes the photosensitive surface inside the box and reflects it.

  3. It sets out the mathematical relationship between the coordinates of a point in a 3-D space and their projection onto the image plane of an ideal pinhole camera.

  4. Here, we consider the camera’s aperture as a point and no lenses are used to focus the light as the light rays coming from an object converge to pass them through that small hole of the camera

Image Formed by Pinhole Camera

From the above construction, let’s discuss the characteristics of the image formed by a pinhole camera:

  1. The size of the image formed by the pinhole camera is smaller than the size of the object and appears inverted on both vertical and horizontal axis when compared with the actual object.

  2. The image formed is real because it is visible on the screen.

  3. The rays coming from an object converge to pass it through the hole of the pinhole camera.

  4. The size of the hole determines the sharpness of the image that means less the size of the hole, sharper the image will be, and vice versa.

Uses of Pinhole Camera

  1. We can project the image formed by a pinhole camera on a translucent surface for a real-time and safe observation of the solar eclipse.

  2. We can use these cameras for surveillance as they are difficult to detect.

  3. A useful device to observe the reflected image of a dazzling object such as the Sun.

  4. Most applications use pinhole camera models for studying the movement of the Sun over a lengthy period (a process known as Solagraphy).

  5. The device helps the artist to view a scene through a unique perspective.

Do You Know?

The functioning of a pinhole camera is like that of a human eye because in a pinhole camera, the light passes via the pinhole of the camera to project an upside-down image onto the back of the box, while in the human eye, light passes through the lens to produce an upside-down image on the back of the retina. The brain then flips that image so we experience it with the right side up.

FAQ (Frequently Asked Questions)

1. Why is the image in a pinhole camera inverted?

Pinhole camera forms an inverted image because the light rays coming from the top and bottom of the object intersect at the pinhole and converge to pass via a tiny hole. Thus, we get an upside-down image in a pinhole camera because of recti-linear or a straight propagation of light through the hole of the pinhole camera.

2. Why are pinhole cameras used?

A pinhole camera can trace the image on a piece of paper or on the film to achieve a very accurate copy of the scene. The size of the hole decides the sharpness of the image formed on the scene. If we increase the size of the hole, the more light would enter the hole and would disturb the formation of the image and we would get the blurred image. It’s better to mark a small hole. Therefore, small is the aperture, it forms the sharp image on the screen.