GT Explains: What is Aperture and Why is it Important in Photography

Namrata Gogoi

Ever since the days of the pinhole camera, aperture has played a key role in deciding how a photo turns out. In fact, it's one of the fundamental concepts of photography and can make or break a photo.

What Is Aperture

However, with the advent of DSLRs and Point and Shoot cameras, most of us have gotten used to the Auto mode in these cameras. 

All you need to do is press the shutter button and the camera will do the job of adjusting the exposure levels, brightness, etc. But at the end of the day, the auto mode is not the answer if you want to explore the full potential of your camera. 

To do so, you'll have to fully understand the basic concepts of photography and that includes Aperture, Shutter Speed, and ISO.

In this post today, we'll explain what is aperture and why is it important in photography.

What is Aperture?

Aperture is one of the three principal building blocks of photography and is responsible for controlling the amount of light that reaches the camera sensor. In a nutshell, the aperture decides how dark or bright a photo will be. More importantly, this factor also decides how much of an image shall stay in focus.

The aperture decides how dark or bright a photo will be

What Is Aperture

Technically, aperture refers to the opening of the camera lens. A bigger opening means more light can travel to the sensor and thus a bright photo. On the other hand, a smaller opening will make the images dark.

To put it simply, aperture alters the exposure of the image.

How is Aperture Calculated?

Aperture is generally calibrated in f/stops. The lower the f/stop, the wider is the opening and vice versa. Hence, a camera with an aperture of f/2.2 will capture more light than a camera with a narrow aperture such as  f/5.6. 

462Px Aperture Diagram Svg
Source: Wikipedia
To put it simply, small f/stops numbers are large apertures and big f/stops are small apertures.

How Does Aperture Impact Depth of Field

Aperture doesn't just affect the exposure of an image. It also affects the depth of field (DoF), a critical aspect of photography. In fact, DoF is one of the beauties of aperture. 

Med Aperture
Image captured with f/3.5 aperture, ISO speed of 250 with an exposure time of 1/50 sec
The depth of field is the area that stays in sharp focus. Interestingly, there are two kinds of depth of field — shallow and deep. A shallow depth of field means that the background is blurry and a deep depth of field means that the entire picture is in sharp focus has a large/deep depth of field.
Narrow Aperture
Image captured with f/2.8 aperture, ISO speed of 250 with an exposure time of 1/50 sec
So, the formula goes something like this. Wider the aperture, the shallower is the depth of field, and narrower the aperture, the greater is the depth of field.

In a nutshell,

  • Low f/stop = Wide aperture = Shallower DoF = More blur
  • High f/stop = Narrow aperture = Deep DoF = Sharper image

Thus, a wide aperture lens (like f2.8) is ideal for portrait photography where the object is kept in sharp focus and the background gently blurs away. Quite obviously, the reverse holds true. A narrow aperture (like f/8) is ideal for capturing landscapes and cityscapes where the background and foreground are in sharp focus.

How Does Aperture Impact Shutter Speed

Another area of impact is the shutter speed. Using a low f/stop means that there is more light entering and thus, the shutter needn't stay open that long. 

Aperture In Photography

On the other hand, a high f/stop translates into slow shutter speed.

How is Smartphone Aperture Different?

Unlike DSLRs, where we can manually adjust the aperture, shutter speed or the ISO, almost all smartphones have fixed aperture. Now, owing to the small area in a smartphone, the image sensor and the lens used are much small. 

2

Owing to the short focal length (smaller distance between the sensors and the lens) you get a broad field of view, hence, a much wide angle. So, instead of getting a blurry background, a smartphone camera will instead get you a clear and distinct background at the same aperture, even though it's a wide aperture.

Aperture

That said, smartphone apertures are a lot different then DSLR apertures. For starters, you wouldn't get the same level of finish or depth of field. A f/2.2 smartphone aperture is equivalent to f/8 -f/10 in a DSLR camera.

What About Dual Aperture on Smartphones?

Now, even phones have started experimenting with aperture. The Samsung Galaxy S9 Plus is the first smartphone to come with a dual aperture camera. It can switch between f/2.4 and f/1.5. Though it doesn't switch in the auto mode, you can manually adjust it in the Pro mode. 

So, this was why aperture is important in photography. If you have any questions, do share them with us in the comments section below.

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Namrata Gogoi

Written By

Namrata Gogoi

An engineer turned tech writer, Namrata used to write software codes before turning to a career in tech- writing. She is passionate about travelling, food and reading about cool new stuff. Apart from that, she holds a bachelors degree in I.T and hails from Guwahati.