What is a Camera and What Are Photographs?

compact camera Have you ever asked yourself: what is a camera exactly and how does it work?

Well, all cameras work by focussing and recording light. In the old days, the simplest cameras were boxes that had a hole to let light in and a lens to focus it onto a film, which recorded the picture. The basic idea is the same today except that most people use digital cameras, which record the light onto a sensor instead of a film.

What is a film camera?

film cameraUntil recently all cameras used photographic film to record the picture. Film is a plastic sheet coated with chemicals that react to light to record the image. Pictures taken with a film camera need to be developed before they become photographs, and they cannot be exported as files on a computer.

Film cameras used to take better pictures than digital cameras, but this is no longer the case. Today, film cameras are quite rare, in part because it is much less convenient and more expensive to take lots of pictures when you have to go to a shop and have them developed before you can use them. Also it is much harder to share them with your friends when the photos cannot be exported as files on your computer.

What is a digital camera?

Digital cameras record light on a digital sensor. This means that you can take as many photos as you like until your memory card is full and you can easily erase the photos you do not like. Also, a photo can be saved as a file on your computer, which makes it much easier to share your pictures.

Since film cameras are very uncommon today, we will only talk about digital cameras on this site.

camera cutaway

How are digital photos created?

To understand how photos are created, you need to know the basic parts of a camera:

  • The sensor: The sensor is a digital chip located behind the shutter. The sensor records a picture when light shines on it.
  • The shutter: This is like a curtain which covers the sensor. When the shutter opens,
  • The lens: Lenses are pieces of glass or plastic that focus light onto a sensor. Lens are necessary so that photos do not look blurry.
  • The aperture: This is the opening directly behind the lens. The bigger or wider this opening, the more light is allowed in to the sensor. This is why you might hear photographers talk about using a "wide aperture" when taking pictures in the evening when there is little light.
  • Memory card: This is where your camera stores the pictures you take. It is a lot like the hard disk on your computer.

So, this is how a digital picture is taken:

photographer When you point the camera at something and see an image, the first thing you need to do is make sure that the image is in focus. Images that are in focus appear sharp while those out of focus look blurry. Some cameras do this automatically and some do not, but in both cases the lens is moved so as to focus the light.

Once the image looks good and you press the button to take the photo, the shutter opens and shuts very quickly, letting a little bit of light touch the sensor. This light is recorded by the sensor and a photograph is saved on your memory card.

Hopefully you now have a basic grasp of what a camera is. If you want to read more about it and if you think you can handle an article intended for grownups, you can find a wealth of information in this Wikipedia article.

by Simon James Allanach, edited by Alan Frost
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