What is exposure triangle?

Exposure triangle consists of 3 elements present in all professional digital photography cameras. These 3 elements are aperture, shutter speed and ISO.
Gaurav Achpalea

What is Creative Life?
Creative Life is a series through which I share my knowledge about photography and videography skills. Both these crafts have become quintessential for people wanting to become digital content creators. The more you develop these skills the more you raise the production value of your digital content. This eventually could translate into producing quality content that has the potential of gaining traction and popularity with time.

The professional photography market is today flooded with camera bodies that suit different budgets. Be it an entry-level basic crop sensor DSLR or a fancy Medium Format DSLR, they all have one thing in common. Yes, you have guessed it right! I am talking about the exposure triangle. 

So what exactly is the exposure triangle? As the name suggests, it consists of 3 elements present in all professional digital photography cameras. These 3 elements are aperture, shutter speed and ISO. 

Regardless of the camera you pick, you need to learn how to manipulate these 3 elements to get a perfect shot. While an absolute beginner would mostly use the auto mode built-in these modern cameras, the amateur would try to stay in either shutter priority or aperture priority mode. The experienced professional photographer though, would stay in the full manual mode as much as possible. Only when the external lighting conditions are rapidly changing or if the subject is constantly moving, the professional photographer would stick to either aperture priority or shutter priority mode. 

So to understand the exposure triangle well, you need to first understand how each element contributes to the final image. Once that bit is clear to you, then you just need to get your head around how these three work in tandem.

Aperture is the opening through which the light travels to reach the imaging sensors placed with camera bodies. The aperture setting is lens-specific which refers to how wide or how narrow a lens can open up in order to let the light fall on the imaging sensor inside the camera. The size of the aperture opening is expressed in f-stops. The wider the opening, the lower the number of the f-stop. The bigger the number of the f-stop the narrower the opening. 

The widest possible lens opening lets in maximum light and as the opening gets narrower the lesser the light that seeps through the lens onto the imaging sensor. However, one more important reason why aperture is of importance is because of the depth of field. A wide aperture results in more blur due to shallow depth of field. The narrower the aperture the sharper the image becomes overall with less blurred areas.

So, to sum it all up… aperture has a direct impact on the focal range/depth of field and amount of light in your final image.

Shutter speed:
Shutter speed refers to the duration of the camera’s imaging sensor being exposed to the light entering the camera through the lens opening. The amount of light that gets registered in the final image is hence proportional to the exposure time. The longer the duration, the more the light and vice versa. Shutter speed is expressed in seconds or fractions of it. 

Another way in which shutter speed can dramatically impact the final image that gets captured by your camera is through motion blur. This photography phenomenon becomes pronounced when the image has a moving subject. Light trails from stars, cars, etc. are the most common examples of creative motion blur. However, the same can be noticed when photographing a waterfall, for example. Slower shutter speed will result in giving a more and blurred flowy effect to the water. As the shutter speed increases the water will look sharper with even droplets being captured clearly at fast shutter speeds. However, if you are photographing perfectly still imagery, like product photography on a still background in a controlled studio environment, the motion blur element due to slow shutter speed becomes almost negligible. The only thing that can add some blur in such a situation is the internal camera vibration itself that is either caused due to shutter opening and closing or mirror moving to reflect light in DSLR cameras. Another reason why the modern mirrorless cameras have a slight edge over the conventional DSLR cameras.

So, to sum it all up… aperture has a direct impact on the motion blur and amount of light in your final image.

The sensitivity of the imaging sensor to light is defined by your ISO settings. The general rule of thumb is to keep the ISO setting at the lowest possible and tinker with it only if necessary. This is because higher ISO makes the image grainy. These grains are most prominent in the darker parts of the image and are often referred to by the term ‘noise’ by many professional photographers. So if a professional photographer says ‘there is so much noise in this photo’ he is referring to the grainy parts of the image.

So, to sum it all up… think of ISO to be a hack or a sort of cheat code that one should only use in situations where it is tough to get the desired exposure value by tweaking aperture and/or shutter speed settings. It is always ideal to restrict the ISO at the lowest possible setting to get the best possible image from your camera.

How do they work in tandem?
So now you might have already got some idea how these three elements work in combination for getting the exposure right in your images. If not, here’s some more clarity…Multiple combinations of shutter speed and f-number can give the same exposure value. A shutter speed of ​1⁄125 sec with an f/5.6 aperture gives the same exposure value as a ​1⁄250 sec shutter speed with an f/4 aperture. So the art really is to set one element at a certain level to achieve a creative effect (like background blur or motion blur) and then compensate for it using the other element in the exposure triangle and arrive at the required exposure value in the final image. ISO should ideally only be brought into play when it is not desirable to use slow shutter speeds or wide apertures.

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