Photography Basics #1: How a Digital Camera Works

Michael Sand
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How a Digital Camera Works: Understanding the Key Parts

Your digital camera uses basic imaging principles to take, process and store pictures. The entire process begins with converting light captured onto the camera into digital information, and is carried on by various imaging processors. This is interesting, but doesn’t tell us enough about how a digital camera works.

So let’s dissect your camera and see how the key components and features come together to create a powerful and versatile device.

There are two major sections on a digital camera: an optical system and an imaging system. The two merge into one in your digital camera, but for the purposes of our discussion, we’ll separate them. Hence below

The optical system is what you use to take pictures with the camera. It’s composed of the:

  • Aperture
  • Lens
  • Exposing sensor
  • and a light sensor

The imaging system is responsible for capturing light and converting it into digital information. The essential parts of the imaging system are comprised of:

The shutter

Camera Lenses

The key to better pictures is the lens. The better the lens, the better the picture. But in the days of digital,…

It’s easy to think that a camera with a better sensor will always be the best choice. A better lens and image sensor will always result in better image quality. A good lens doesn’t always pair well with a bad image sensor.

Both the lens and the image sensor play a critical role in image quality. A high-end sensor will only show its true potential if it is paired with a good lens and a high-quality lens will have less impact on an average image sensor.

You don’t need a high-end camera. But you do need to buy the right camera for the type of pictures you want to take.

Image Sensor

The image sensor is a light capturing device. The information captured is converted into data.

The image sensor is also known as the "film" in digital cameras. The sensor is what allows you to take photos with a digital camera.

It's either made from CCD (charge-coupled device) or CMOS (complementary metal-oxide semiconductor). In a digital camera, there are usually multiple sensors inside the camera that are all working together to make the image on your screen or computer.

So how does an image sensor capture an image?

Imagine that the image sensor is a bucket and the opening of the bucket is exposed to light. The surface of the image sensor is a grid of cells, corresponding to pixels that capture the light arriving onto them. There is a horizontal line of cells and a vertical line of sensors, with those two lines corresponding to one "pixel" of your photo.

How many pixels are there in an image sensor?

If you have a top-of-the-line DSLR camera, the typical image sensor size is 24 x 36mm and with around 18MP that means it captures images with a resolution of around 5000 x 7000 pixels.

Of course, smaller image sensors are used in portable cameras and cell phones.

Other Camera Basics

Why Different Photo Formats Matter?

Correct Camera Settings: The Essentials

How a Digital Camera Works

There are two main types of cameras; analog and digital. And both work in the same way. They move a light-sensitive piece of plastic (called film) in front of the lens.

The light is focused on the piece of film which gets exposed to it.

The difference between an analog and a digital camera is how the exposed film negative gets developed.

In analog photography, the entire piece of exposed film is removed from the camera and developed. And in digital photography, an electronic sensor (with electronic circuitry) is exposed to the light, taking the place of the film. A series of electronic charges is transmitted from the sensor to create the digital image or photograph we are used to seeing on the screen of our devices.

There is also a third type called a hybrid camera. It’s a combination of analog and digital technology. I will not discuss hybrid cameras here.

There are a few simple steps in the process of making an exposure on digital camera.

First, the light entering the lens needs to be focused on a sensor. So the lens is moved closer to or away from the sensor to bring the light into focus.

Then a shutter operates at the speed you select to allow entry of light to the sensor.

The sensor converts the light to electrical charges and digitizes them to create a digital image.