Explaining photography and the exposure triangle to a novice can be done using simple terms and easy-to-understand analogies. Here’s a detailed explanation that covers the basics while remaining accessible.

Introduction to Photography

Photography is the art of capturing light to create an image. To get the perfect shot, you need to master three key elements that make up the exposure triangle: aperture, shutter speed and ISO sensitivity. These three parameters control the amount of light reaching the camera’s sensor, and must be balanced to achieve the right exposure.

The Exhibition Triangle

Aperture :

• • What is it?
    • Aperture refers to the size of the opening in the camera lens, through which light enters. It is measured in f-stops (such as f/2.8, f/4, f/8, etc.).
  • How does it work?
    • A small f value (such as f/2.8) means a large aperture, letting in more light. A large f value (such as f/16) means a small aperture, letting in less light.
  • Photo effect:
    • A large aperture (small f-stop) creates a shallow depth of field, meaning that the subject is sharp while the background is blurred (bokeh effect). A small aperture (large f-stop) creates a large depth of field, meaning that more of the scene is in focus.

Shutter Speed :

1. • What is it?
     • Shutter speed refers to the time during which the camera shutter remains open to allow light to reach the sensor. It is measured in seconds or fractions of a second (such as 1/250, 1/60, 1″, etc.).
   • How does it work?
     • A fast shutter speed (such as 1/1000) lets in less light, but can freeze moving subjects. A slow shutter speed (such as 1/30) lets in more light, but can cause motion blur.
   • Photo effect:
     • Fast shutter speeds capture sharp actions, ideal for moving subjects. A slow shutter speed can create blurred effects to show movement, such as the light trails of car headlights at night.

1. ISO sensitivity :
   • What is it?
     • ISO measures the sensitivity of the camera sensor to light. Common ISO values are 100, 200, 400, 800, etc.
   • How does it work?
     • A low ISO value (such as 100) means low light sensitivity, requiring more light for good exposure. A high ISO value (such as 1600) means high light sensitivity, enabling photos to be taken in low-light conditions.
   • Photo effect:
     • Low ISO produces high-quality images with little digital noise (grain). High ISO can introduce noise, reducing image quality.

How to Balance the Exhibition Triangle?

To get the right exposure, you need to balance these three parameters. Here are a few scenarios to illustrate:

• Daylight (lots of light):
  • Use a low ISO (100-200).
  • A fast shutter speed (such as 1/500) to avoid overexposure.
  • A medium aperture (like f/8) for good depth of field.

• Indoors/low light :
  • Increase ISO (400-1600) to capture more light.
  • Use a wide aperture (such as f/2.8) to let in more light.
  • A slower shutter speed (such as 1/60), but make sure you don’t introduce motion blur.

Practical example

Let’s say you’re taking a photo of a moving person at an indoor event in subdued light:

• Aperture: f/2.8 (large aperture to let in more light and isolate the subject with a blurred background).
• Shutter speed: 1/250 (fast enough to freeze movement).
• ISO: 800 (to compensate for low light without too much noise).

By adjusting these parameters, you can control the amount of light and how it affects your image, creating a well-exposed and aesthetically pleasing photo.

The key is to understand how these three elements interact, and to adjust them according to lighting conditions and the desired effect. By practicing and experimenting, you’ll become more comfortable using the exposure triangle to get perfect photos.

Stéphane Clément