# How does a pinhole camera works ?

Working of a Pinhole Camera
The image is formed when a light is reflected back from the object.
Let us understand how image is formed in a pinhole camera by taking a practical example.
Suppose you are inside your house and there is a tree in front of one of the window of the house. Now take a cardboard make a small hole in it and place it parallel to the window. Look from the hole you will observe that if you move to the right a bit, you will see the left of the tree. If you move up, you will see further down the tree. Your view of the tree is just opposite to the direction of your movement.
Now cover the window such that light only passes through the hole. The image of the tree on the wall will be upside down. The ray diagram below will make it clear.

The room here in above example is what we call camera obscura in the pinhole camera. Now, when the plates of the pinhole camera are exposed to the reflected light we get inverted image.
This is how the image formation in pinhole camera takes place.

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pin hole camera can be made with simple materials and can be used to image the sun and brightly lit objects

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A pinhole camera is the simplest camera possible. It consists of alight-proof box, some sort of filmand a pinhole. The pinhole is simply an extremely small hole like you would make with the tip of a pin in a piece of thick aluminum foil.

A pinhole camera works on a simple principle. Imagine you are inside a large, dark, room-sized box containing a pinhole. Imagine that outside the room is a friend with a flashlight, and he is shining the flashlight at different angles through the pinhole. When you look at the wall opposite the pinhole, what you will see is a small dot created by the flashlight's beam shining through the pinhole. The small dot will move as your friend moves his flashlight. The smaller the pinhole (within limits), the smaller and sharper the point of light that the flashlight creates.

Now imagine that you take your large, dark, pinhole-equipped room outside and you point it at a nice landscape scene. When you look at the wall opposite the pinhole, what you will see is an inverted andreversed image of the scene outside. Each point in the scene emits light, and, just like the flashlight, the beam of light from that point passes through the pinhole and creates a point of light on the back wall. All of the points in the scene do that at the same time, so an entire image, in focus, is created on the back wall of the room. The image is very dim because the pinhole is so small, but you can see it if the room is very dark.

A pinhole camera is simply a smaller version of that room, and the film inside the camera replaces you. The film records the image that comes in through the pinhole. The camera records a nice, in-focus image of the scene that you point the camera at. Usually, you have to expose the film for a long time because the pinhole lets so little light through.

The pinhole in a pinhole camera acts as the lens. The pinhole forces every point emitting light in the scene to form a small point on the film, so the image is crisp. The reason a normal camera uses a lens rather than a pinhole is because the lens creates a much larger hole through which light can make it onto the film, meaning the film can be exposed faster.

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A pinhole camera is the simplest camera possible. It consists of alight-proof box, some sort of filmand a pinhole. The pinhole is simply an extremely small hole like you would make with the tip of a pin in a piece of thick aluminum foil.

A pinhole camera works on a simple principle. Imagine you are inside a large, dark, room-sized box containing a pinhole. Imagine that outside the room is a friend with a flashlight, and he is shining the flashlight at different angles through the pinhole. When you look at the wall opposite the pinhole, what you will see is a small dot created by the flashlight's beam shining through the pinhole. The small dot will move as your friend moves his flashlight. The smaller the pinhole (within limits), the smaller and sharper the point of light that the flashlight creates.

Now imagine that you take your large, dark, pinhole-equipped room outside and you point it at a nice landscape scene. When you look at the wall opposite the pinhole, what you will see is an inverted andreversed image of the scene outside. Each point in the scene emits light, and, just like the flashlight, the beam of light from that point passes through the pinhole and creates a point of light on the back wall. All of the points in the scene do that at the same time, so an entire image, in focus, is created on the back wall of the room. The image is very dim because the pinhole is so small, but you can see it if the room is very dark.

A pinhole camera is simply a smaller version of that room, and the film inside the camera replaces you. The film records the image that comes in through the pinhole. The camera records a nice, in-focus image of the scene that you point the camera at. Usually, you have to expose the film for a long time because the pinhole lets so little light through.

The pinhole in a pinhole camera acts as the lens. The pinhole forces every point emitting light in the scene to form a small point on the film, so the image is crisp. The reason a normal camera uses a lens rather than a pinhole is because the lens creates a much larger hole through which light can make it onto the film, meaning the film can be exposed faster.

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Now, we will summarise what we have learned so far.

• A pinhole camera is a simple optical device that forms an image without using a lens or a mirror.

Construction of a Pinhole Camera

Here is a graphical representation of a simple pinhole camera.

• Did you know that a pinhole camera does not require a lens or a mirror for image formation?

• A Chinese scholar invented the pinhole camera in 400 B.C.

Working principle of a Pinhole Camera

The size and contrast of the formed image can be changed by sliding the smaller cylinder. In addition, the image also depends on the size of the pinhole; the smaller the pinhole, the sharper will be the image and vice-versa.

Try looking at your own hand through a pinhole camera. You will observe an upside down image of your hand. Now, move your hand downwards slowly.What do you observe on the screen?You will observe that the image of your hand is moving upwards.

A pinhole camera creates a real image of an object, because the image can be captured on a screen. The image formed by a pinhole camera isinvertedandsmallerthan the object.

Construct your own pinhole camera and look at the sun during a solar eclipse. Avoid looking at the sun directly.

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