Understanding the Exposure Triangle

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For any budding photographer, understanding the exposure triangle is one of the first steps in their journey towards capturing perfect photos. The purpose of exposure triangle is to ensure the clicked images have the right exposure. In simple terms, exposure refers to how light or dark an image will appear. The perfect light setting is essential to avoid images getting underexposed (too dark) or overexposed (too bright.) Mastering exposure is considered as one of the basic photography techniques.

In a camera, exposure is determined by three key variables: aperture, ISO and shutter speed, also known as the ‘Exposure Triangle.’ Apart from light, exposure triangle also influences whether images are noisy/blurry or crisp and sharp. In this article, we explain the ‘Exposure Triangle’ in detail.

Aperture:

To put simply, aperture refers to opening of the lens, which allows light to travel into the camera. To draw parallels with humans, aperture is very much similar to pupil in the human eye; the pupil is a hole that allows light to enter the eye. The bigger the aperture, more light enters the sensor. So, if you double the opening or the aperture, the amount of light hitting the sensor is doubled.
Aperture is expressed in f-numbers, such as f/2.8, f/4, f/5.6 and so on. These numbers, also known as f-stops, are used for describing the openness/closeness of the aperture. Interestingly, when it comes to f-stops, a larger number means a smaller aperture or a smaller opening, whereas a smaller number refers to a larger aperture opening. So, an aperture setting of f/2.8 gives a larger opening, resulting in more light coming through as compared to an aperture of f/5.6. Whereas, an aperture of f/11.0 will give a much smaller opening, leading to much less light entering than say an aperture of f/4.

 


Image Credit: Todd Vorenkamp

 

ISO:

In a camera, sensitivity is controlled by an “image sensor” or sensor. The sensor plays a critical role of collecting light and transforming it into an image, thereby making it the most crucial and expensive part of any camera.
ISO determines how sensitive a camera is to available light. ISO numbers start from 100 and go up to 200, 400, 600 and so on. A higher ISO number of say 3200 or 6400 means the camera is more sensitive to light, whereas with a lower ISO number like 100 or 200 the camera is less sensitive to light. A higher ISO allows the camera to capture images even in low light without using flash. However, a drawback of higher ISO is the addition of visual noise to the image. It is advisable to stick to the base ISO (100-200) for optimum image quality.