How does camera work?

Answer 1

In film cameras, there are chemicals that change their nature when exposed to light.

Light from the sun and other sources reflects off of objects and is focused by a glass lens, at the end of the lens is an aperture control, a diaphragm that opens and closes to allow more or less light through the lens. At the rear of the camera (just in front of the film or light sensor) is a shutter. The shutter is in the form of several curtains that expose the film/light sensor to a consistent amount of light across the entire film/sensor. The amount of time the shutter is open helps determine how much light will reach the sensor.

If you want to know how a camera works, here:

If you are looking at an image the light bouncing off the object you are photographing, passes into the camera, through a set of lenses and onto a mirror. From there, the light bounces up and into a piece of glass called a pentaprism (a five sided prism). Once light enters the pentaprism, it bounces around in a complicated way until it passes through the eyepiece and enters your eye.

If you are looking at a photo, when you press the button on the camera, the mirror flips up, in front of the pentaprism. Instead of the light from the object bouncing on the pentaprism, the light passes directly to the back of the camera. There, it either hits photographic film or starts a chemical reaction (single use camera), or the light it impacts on a ray of light-sensitive cells that release a tiny electric charge in each activated cell (digital camera).
There are several types of camera.

The old style, using photosensitive film and chemicals. This works by having a light proof box with the film stretched across the inside.

A shutter lets light in, for a brief period, when the shutter release button is pressed. The light passes through a glass lens which focuses a picture onto the back of the inside of the camera, where the film is. The light leaves a chemical change on the photosensitive emulsion, which is invisible until processed.

After the film has been used, it has to be kept dark (in a cassette) until processed with chemicals.

That is the basics. Cameras will vary in complexity on how much adjustment of the functions are allowed, such as shutter speed, aperature, focus and automation.

Digital cameras.

The box remains the same as a film camera. Instead of the film, there is a semiconductor chip, with an open sensitive surface, onto which the picture is focused by the lens. This is commonly a Charge Coupled Device (CCD).

The chip is made up of a grid of photo sensitive pixels, the electrons are knocked off by the light, in varying degrees and leave a charge in that area.

A computer, built within the camera, can access each of the pixels, assigns a digital value, depending on the amount of charge (light) and then write this value to a file, which is then stored in non-volatile memory.

Some cameras have internal memory and others (commonly) have a removeable memory card.

The picture files can then be accessed by a cable, or removing the memory card.

Once downloaded onto another computer or printer, the pictures can then be printed using ink jet or laser printers, onto normal or glossy paper.