Untangling the exposure triangle

If you’ve been following my articles, then you probably have a basic knowledge about the three pillars of exposure — aperture, shutter speed and ISO. In this article, we’re going to understand how they come together forthe perfect exposure. Before we get into it, here’s a quick recap.

Shutter speed is the length of time a camera shutter opens to expose light into the camera sensor. Aperture is the size of the opening in your DSLR’s lens, which helps determine the amount of light that reaches the camera’s sensor. And finally, ISO is the level of your camera’s sensitivity to light.

What is the exposure triangle?

The ‘exposure triangle’ occurs when these three elements — aperture, shutter speed and ISO — work together to provide enough light so the camera can record what you see. For the perfect exposure, you need the right combination of these three components. An underexposed photo occurs when you don’t let in enough light, therefore making it too dark, and overexposure occurs when you let in too much light, making it too bright, and hence, less detailed.

The window

Since the relationship between shutter speed, aperture and ISO is a little complicated, there are a number of metaphors people use to explain it. Here’s one I find helpful –— the window. Imagine your camera is like a window with shutters that open and close. The aperture is the size of the window –— the bigger it is, the more light goes through and brightens the room. Shutter speed is the amount of time that the shutters are open for. Obviously, the longer it is open, the more light comes in. And finally, for ISO — imagine you’re sitting in the room and wearing sunglasses, desensitising you eyes to the light that’s coming in through the window (like a low ISO.) If you want to see more light in the room, you can either increase the duration for which the shutters are open (decrease shutter speed), increase the size of the window (increase aperture) or take off your sunglasses (increase the ISO).

How it all comes together

ISO, shutter speed, and aperture are known as the exposure triangle because changing one side of the triangle affects the other two sides. It takes a lot of practice to understand and master the exposure triangle, and even professional photographers spend a lot of time experimenting with their settings and tweaking them to get the perfect exposure.

The most important thing you have to remember is that when you change one aspect of the triangle, it not only has an effect on the exposure of the image, but also has an impact on the other aspects of the image. For instance, changing the aperture affects the depth of field, changing the ISO changes the details in the image, and changing the shutter speed has an impact on how motion is captured.

An easy way to get started with your settings is to shoot on aperture priority mode. That way, you can adjust the aperture, while the camera automatically sets the shutter speed and ISO. As always, practice makes perfect, and the more you experiment with each side of the triangle, the better your photos will get.