A is for Aesthetic

Understanding the creative aspect of lens aperture

Song sparrow calling, La Jolla, CA | ©Jason P. Odell

In Photography 101, we were taught that aperture is a physical property of your lens, and you can vary its size to control the amount of light entering your camera. Usually, we think of aperture as it relates to the rules of exposure, because that’s where the impact is most noticeable in the field.

Back when I was shooting film and early digital cameras, it was considered ideal to have a “fast” lens— one with an aperture of f/2.8 or wider. Why? because with limited ISO options (remember film rarely was faster than ISO 800 and early DSLRs got noisy in a hurry above ISO 400), a fast lens meant you could shoot hand-held in dim conditions without a flash, or use fast shutter speeds for capturing action in reasonably lit scenes.

Today, ISO isn’t the limitation it used to be. Sure, images are still cleaner and have greater dynamic range at a camera’s base ISO, but you can shoot above ISO 6400 these days pretty much with impunity. That means you have much more creative latitude to choose the aesthetic of your shots by varying the lens aperture.

Depth of field as a creative tool

If you ask a non-photographer what makes a shot look “professional,” they might not know the right answer but it almost always comes down to depth of field. Smartphone cameras and most point and shoot cameras have sensors that are so small that everything is sharp from foreground to background. That kind of look is fine for landscapes (Ansel Adams was a member of the f/64 club, after all), but isolated subjects with smooth, out of focus backgrounds create a unique look in photographs. It’s why smartphone makers have started implementing computational photography tools like “Portrait Mode” in their camera software, and why many photographers gravitate towards Aperture-priority exposure mode.

If you’re using a standard digital camera, depth of field comes down to these four parameters: