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How do cameras work?

All camera's - whether a film camera or digital camera - work by capturing light. They record the amount of light they capture and turn this information into an image.

Camera

Light reflects off objects in all directions. The job of the lens is to take that light and direct it onto the sensor. A lens is made of curved glass which directs the light. The glass in a lens can sometimes move allowing the camera to get closer to a subject or further away.

An illustration of a lightbulb

When you take a photo, the camera shutter opens to let light hit the sensor and then closes. The shutter stays open until it has the light needed to make a picture. It's a bit like opening the door from a dark room into a light room. Light comes in only while the door is open.

An illustration of a door open from a room full of light, letting light into a dark room

A camera can also let more or less light onto the sensor using it's lens. The opening of the lens can be smaller or larger depending on the amount of light the picture needs. This is called the lens aperture.

An illustration of a door open from a room full of light, letting light into a dark room

When light enters the camera through the lens, it is captured on a sensor. A sensor is made up of millions of pixels, little squares which each record how much light hits them and the colour of the light.

An illustration of a camera sensor

Light can be shades of red, green or blue. A blue sky for example is made by a sensor picking up thousands of shades of blue. Each pixel records the amount of red, green and blue (RGB for short) for that single pixel. The RGB number for blue for example would be R=0, G=0, B=255.

An illustration of a camera sensor with colours on each pixel

The camera receives all this information from the sensor and shows the photo digitally back to you.

An illustration of the back of a camera with a photograph viewed on the cameras screen

Film cameras work in a really similar way. But instead of a sensor capturing the colours of light, a film which contains light sensitive crystals captures the chemical change to the crystals. It can then be developed into a photograph.

An illustration of a camera sensor with colours on each pixel