What are the Basic Camera Parts and How Do Cameras Work?

There’s no mistaking it that modern digital cameras are complex machines. There are tons of camera parts that make them work properly and record images as you’ve instructed the camera to do.

The question is, what are the essential parts of a camera? Beyond that, how do cameras work?

In this page, we’ll seek to answer both these questions.

Digital Camera Parts: The Lens

First up is the lens, which, though it isn’t technically part of DSLRs or mirrorless cameras, is the first important component in making cameras work. Its job is to gather and focus light by using a series of glass elements inside its barrel.

The light that comes into the lens is bent, so it is directed onto the camera’s imaging sensor, which lies in the body of the camera. It is on the imaging sensor where the information about the light coming through the lens is recorded.

Obviously, the lens is a crucial component of this process, as without it, the light would not be directed onto the camera’s sensor

There are many different types of lenses, from wide-angle to telephoto and primes to zooms.

For more details on the basics of lenses, check out this tutorial.

The first thing to understand is that when you take an image, the quality of it has much more to do with the lens than the camera.

To summarize: Lenses gather light, focus it, and direct it through a series of glass elements where the focused light hits the camera sensor.

Digital Camera Parts: The Lens Aperture

The aperture of a lens is comprised of multiple blades that open and close, thereby controlling the amount of light that’s allowed into the lens.

The larger the aperture opening, the more light that can reach the camera’s sensor. The smaller the aperture opening, the less light that’s allowed in. You can see how this works in the chart above.

Note that the aperture is measured in f-stops, where a small f-number like f/1.4 represents a very large aperture and a large f-number like f/32 represents a very small aperture.

Likewise, the size of the aperture also influences the depth of field of an image, or the area that’s sharply in focus.

The smaller the f-number (i.e., f/1.4), the smaller the depth of field, like the portrait shown above. Notice how the background is blurry, which helps set the portrait subject apart in the shot.

Conversely, the larger the f-number (i.e., f/32), the larger the depth of field, like the landscape scene in the photo above.

Notice how in this case everything from the foreground to the background is sharply in focus.

To summarize: The aperture of a lens controls the amount of light that enters the lens. The larger the aperture, the more light is available and the shallower the depth of field. The smaller the aperture, less light is available and the larger the depth of field.

Digital Camera Parts: The Camera Shutter

Moving into the camera body, the shutter is the next component involved in how cameras work.

The shutter is responsible for controlling the duration of light. So while the lens gathers light and directs it toward the camera’s sensor, the camera’s shutter acts as a gatekeeper for the light - if the shutter isn’t open, light does not pass to the sensor.

When the shutter button on a camera is pressed, the shutter opens for a period of time during which light hits the imaging sensor.

The duration of time the shutter is open ranges far and wide. For example, on professional cameras, the shutter speed might be as short as 1/8000th of a second. On the other hand, most cameras have shutter speeds as long as 30 seconds, and when the camera is in Bulb Mode, the shutter can be held open for minutes or hours at a time.

Most typically, however, photographers use shutter speeds between 1/4000th of a second and 10 seconds.

In addition to controlling how long light hits the camera’s sensor, the shutter speed is also responsible for how action is captured in an image.

Short shutter speeds will freeze movement of most subjects, like the runner in the image above.

Long shutter speeds result in blurred movement, like the waterfall in the photo above, because its motion is recorded over several seconds.

Naturally, the speed of the subject will determine the shutter speed you need to either freeze or blur its movement - to freeze the motion of a hummingbird’s wings, you’d need a much faster shutter speed than if you wanted to freeze the movement of a child playing soccer.

In summary: The shutter speed is the gatekeeper of light and determines how long the light is allowed to hit the imaging sensor. Longer shutter speeds result in blurred movement while shorter shutter speeds are needed to freeze movement.

Digital Camera Parts: ISO

Though ISO isn’t a mechanical part of the camera, it works with the aperture and shutter speed to control the exposure of the images you take.

Where the aperture determines the amount of light and the shutter speed controls the duration of light, the ISO determines the sensitivity of the camera sensor to light.

ISO is measured on a scale, where smaller numbers (i.e., ISO 100) indicate less sensitivity to light and larger numbers (i.e., ISO 6400) indicate greater sensitivity to light.

ISO is also responsible for how much digital noise there is in an image.

Digital noise looks like film grain, and can be used as an artistic element to create an image that looks gritty and raw, like the black and white photo above.

However, in most situations, photographers endeavor to minimize digital noise, and thereby seek to minimize the ISO value to do so.

In summary: ISO determines the sensitivity of a digital camera’s sensor to light. The higher the ISO setting, the more sensitive the camera is to light and the more grain that will appear in the image. The lower the ISO setting, the less sensitive the camera is to light and the less grain that will appear.

It’s important to note that while aperture, shutter speed, and ISO have their individual duties and effects on your images, they also work together to help create each exposure.

When shooting in full auto mode, the camera controls all three settings, sometimes with good results, but often with a less-than-desirable outcome.

By learning how the exposure triangle works and how to manipulate each of these three settings on your own, you will have more control over how an image looks and will be better prepared to create an image that’s well-exposed.

Digital Camera Parts: The Camera Sensor

Clearly, one of the most important parts of a camera is the imaging sensor.

As noted earlier, the sensor is where the focused light from the lens is directed and recorded. The information about light is recorded by millions of photosites, or pixels.

Imaging sensors are measured in megapixels, like 12-megapixels and 24-megapixels. Each megapixel contains one million pixels.

As you might imagine, the more pixels there are, the more light information that can be captured. As a result, these images are generally of a higher quality than lower-megapixel images, at least from the standpoint of color rendition, contrast, and dynamic range, to name a few. This is why professional photographers tend to utilize full frame cameras with large imaging sensors rather than micro four-thirds or compact cameras, which have comparatively tiny imaging sensors, as shown in the graphic above.

This isn’t to say that high-quality photographs can’t be taken with cameras that have small sensors - far from it. However, larger sensors enable photographers to produce higher-quality images thanks to the improved light-gathering power of larger sensors.

Our tutorial on camera sensor sizes goes deeper into this issue. Read it here.

In summary: A camera’s imaging sensor records the light from the lens. The larger the camera sensor, the more capable it is of recording information about color, contrast, and so forth.

How Do Cameras Work?

Though there are many, many other parts of the camera with which you should be familiar, at their core, the lens, aperture, shutter speed, ISO, and imaging sensor are the primary components of capturing photographs.

As noted in the “in summary” notes throughout this tutorial, it is a process that requires many steps, from the lens focusing light to the aperture determining the amount of light to the shutter speed allowing light into the camera. From there, ISO is used to control the sensitivity of the sensor to light, and the sensor’s pixels record the light information to capture an image.

This is a simplistic summary of how cameras work, to be sure. But it gives you the basic notion of what needs to happen for an image to be recorded.

And, with that, you have a quick explanation of camera parts, their functions, and how they work together to help you take a photo!