Photography Basics #1: How a Digital Camera Works

To become a good photographer, you need to know how a digital camera works. In some ways they can be relatively simple, but to really understand how to get the most out of your camera you need to dig a little deeper. You need to know about the key parts of a digital camera, as well as how they interact and affect how your photos come out. We’ll discuss the vital components of a camera, as well as how a digital camera works.

How a Digital Camera Works: Understanding the Key Parts

We’ll cover some of the basics of your digital camera. You may already be familiar with some of them, but it’s good to build your knowledge from the ground up.

Camera Lenses

Canon EF 50mm LensThe lens is an essential part of the camera. It allows light to enter the sensor in order to capture the image. The type of lens you use, as well as the settings of that lens, will determine how your photos look. There’s a wide range of options to choose from, and depending on the type of camera you own you may have either a fixed lens or an interchangeable one. Let’s look at the main types of lens in a bit more detail:

  • Standard/Kit Lens: Cameras, particularly DSLRs, are often paired with a standard kit lens. This is a safe choice of glass for general photography and often has a zoom range. It gives the user the freedom to take a variety of types of photographs, without really excelling at any particular one.
  • Prime Lens: A prime lens has a fixed focal length, meaning the zoom can’t be adjusted. What you see is what you get. Because of this, prime lenses often have a wider maximum aperture, which, as we’ll see, is a benefit for a number of reasons. Prime lenses can produce excellent results in a number of conditions.
  • Macro Lens: If you want to try and get up close to the smaller details of the world and take stunning pictures, a Macro lens is your best bet. They allow users to magnify minuscule details and accurately capture them in a 1:1 ratio.
  • Telephoto Lens: This type of lens is almost the opposite of a macro; it’s what you use to get up close to details that are very far away. The telephoto range is around 70-300mm, and this range can get you up close to the action even if you yourself are physically far away.
  • Wide Angle Lens: Where telephoto lenses are good at focusing in on a small point, a wide angle lens has a wide field of vision and is perfect for capturing landscapes as well as interiors.
  • Specialist Lens: For some unique situations, specialist lenses can be used to create very specific effects. These have little use for general photography, but certainly produce interesting results.

The most important factor about a lens is its focal length (or focal length range). This determines how your photos will look, and the range at which you’ll be able to capture your shot.  As a vague guide, this is how different focal length ranges compare:

  • 8mm – 24mm: Ultra-wide angle (fisheye)
  • 24mm – 35mm: Wide angle
  • 35mm – 85mm: Standard and Prime
  • 85mm – 135mm: Short telephoto
  • 135mm – 300mm: Medium telephoto
  • 300mm+: Super telephoto

Image Sensor

As we mentioned above, the lens allows light to enter the sensor, and it’s this sensor that determines the final quality and resolution of your images. There is a variety of image sensors that are available, and as a general rule, the bigger the better (and more expensive). The sensor also affects the type of lens that you can use with your camera, as well as the relative focal length. Essentially, if the sensor isn’t big enough to effectively use the light that enters through the lens, the focal length range will be cropped to account for this. So for example, an 18-55mm lens will actually give a focal length range close to 27-82mm on a smaller image sensor. Let’s take a look at the sensors you’re most likely to encounter:

  • 1/2.3-inch: These small sensors are often found in inexpensive compact systems. Their small size means that a relatively small body can house them, and a long zoom lens can be coupled with it. They’re becoming less common as technology advances and better quality is desired.
  • 1/1.7-inch: As a slight step up to the 1/2.3-inch mentioned above, a 1/1.7-inch will give an improved level of quality across most areas, and particularly in low lighting. They were popular in enthusiast-level compacts, but the below 1-inch sensor has become increasingly common.
  • 1 inch: Recent years have seen an increase in 1-inch sensors appearing in compact super-zoom cameras. They’re rather versatile, and produce noticeably better quality images than the older, smaller sensors.
  • Micro Four Thirds: Olympus and Panasonic use this format on their compact systems, and it offers a noticeable improvement on the smaller ones.
  • APS-C: APS-C sensors have long been the standard in entry- to mid-level DSLR cameras. Canon use a slightly smaller version than Nikon and Sony, giving a crop factor of 1.6x compared to 1.5x.
  • APS-H: This is an older format of sensor that Canon used to use in their EOS 1D range, and it sits somewhere between a full-frame and APS-C sensor. It’s less common these days.
  • Full-frame: Most professional-level DSLRs will use a full-frame sensor. These are roughly the same size as a 35mm film negative, meaning there’s no crop factor to think about.
  • Medium-format: A relatively new type of sensor, medium-format sensors are bigger than full-frame ones. This allows them to have a higher level of image quality, although the price is still very much out of reach for all but the professional.

Other Camera Basics

Now that we know a little about the two most important parts of your camera, let’s take a look at some of the other technologies you’re going to encounter:

Camera Body

The body of your camera will house all of the key components. There is a vast range available, from the small, inexpensive, compact ones to the huge, bulky, professional-grade ones. Camera bodies will have a variety of controls and options on, and can even be weather and water sealed.


This is how you see what your lens and sensor is about to capture and can take the form of either an LCD screen or a physical part that you look through. Be aware that what you see won’t always be exactly what you capture, so use the viewfinder as a guide for framing your shot.

Mode Dial

In order to select the different settings and modes that your camera is capable of, the mode dial is used. It’s often fairly prominent and allows you to switch between automatic, manual, and pre-set settings. Some older cameras don’t have them, and some newer ones have a touchscreen instead.

Focus Ring

When you’re focusing, the lens and camera will often do most of the work for you, using built-in autofocus. However, many lenses also have a manual focus ring, which allows the user to set the focus point or make minor adjustments.

LCD Screen

The digital age has seen most cameras having an LCD screen. They vary in terms of quality and sophistication, but they will generally show a variety of options and information, act as a viewfinder, and show the final results of your photography.

Shutter Release Button

In order to actually take a picture and fire the shutter, you’ll need to use the shutter release button. It’s very common for a light touch of this to set the autofocus, whilst a full press will activate the shutter and take the photo. The shutter speed determines the amount of time the shutter is open for.

How a Digital Camera Works

We’ve hinted already about how a digital camera works; a digital sensor captures light that enters through the lens #. In essence, a digital camera isn’t hugely different from a film camera in that respect. The amount of available light and how long and how wide the shutter is open will affect the end result. Here’s a simple step-by-step guide as to how it works:

  • The lens is adjusted (automatically or manually) until the subject is in focus.
  • As the shutter release button is pressed, the shutter is opened to allow light through to the digital sensor inside the camera. The amount of time it’s open is determined by the shutter speed; typically the less light there is, the longer it needs to be open.
  • An array of photosensors on the digital sensor detects the pattern and amount of light that enters. When light strikes the photosensors, it returns an electrical current. The combination of all these points of light create the digital image, which is then stored on either a memory card or internal hard drive.

Although there are many different factors that impact this process, this is essentially how a digital camera works.


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