Thoughts on the Exposure Triangle in the Digital Age

Are we reaching the point of unlimited degrees of freedom for setting exposure?

Take any introduction to photography class, and you’ll probably encounter the famous Exposure Triangle diagram. They come in a variety of forms, but the idea is simple: Illustrate the relationships between the three primary drivers of photographic exposure.

• Aperture (ƒ-stop)

• Shutter speed (time)

• ISO (sensitivity of the recording medium)

The Exposure Triangle shows the relationship between aperture, shutter speed, and ISO in photography.

The Exposure Triangle tells us that as long as ONE parameter is fixed, there are multiple combinations for the other two parameters that will allow you to get a proper exposure. With film, ISO was always fixed, which dictated your exposure options. With digital cameras, you can change ISO between shots, giving you much more control over exposure settings.

Of course, photography goes beyond just getting the proper exposure. If all we wanted was a “correct” exposure, you could just set the camera to Program Auto (P) mode and call it a day. But to a trained photographer, exposure is a creative tool in an of itself. The shutter speed and aperture values you choose will have a big impact on the nature of the photograph. Want to freeze action? You’ll want a fast shutter speed. Want a soft background? Use a wide aperture lens.

Each exposure parameter comes with its own consequences, too. Stop down too far and you’ll start to see your images lose detail from diffraction effects. If your shutter speed is too slow, your photos might be blurry unless you have a tripod. As ISO increases, you lose dynamic range and your photos can suffer from digital noise. That being said, I believe that we are now living in an era where we have the technology to make exposure choices that are nearly consequence-free. The rules of exposure haven’t changed (ye canna change the laws of physics, Jim), but we have the tools to bend them quite a bit.

Infinite Exposure Options?

I want to take a moment to go over the key technological advances that give modern digital cameras nearly infinite degrees of freedom when it comes to setting exposure creatively.