Aperture Priority

So, if you are like most beginner photographers, you are afraid to steer away from one of the automatic settings on your SLR. Here's the thing, if you have your camera set to point and shoot, you are ignoring a world of possibilities. How do you make the leap from point and shoot to manual mode? Use one of the semi manual modes such as aperture priority.

To understand the concept of aperture priority, you have to understand aperture. Much like the pupil of your eye, the aperture is an opening that allows light to enter the camera. The larger the aperture, the more light hits the sensor/film.

(*F/ (f stop): The setting on the camera that designates the size of the aperture. It's numbering is inverse to the size of the opening. The smaller the f/, the larger the opening. The larger the f/, the smaller the opening. It's just one of those pesky “to remember” things. Don't worry, there's not a lot of those.)

How does more or less light translate to the picture? The more light, the wider the aperture, the smaller the *f/, and the blurrier the background. You may have heard the term shallow depth of field (DOF). This technique is excellent for portraiture photography. The subject in the foreground is in focus and the background is blurred to bring the attention to the subject.

(“I shot my sister” f/2.8, notice the blurred background, the face is in focus)

The smaller your aperture, the less the light, the more DOF, and the larger the *f/. This is ideal for landscapes where you want everything to be in focus. 

(“Island of Life” f/14.0, notice that everything is in focus. The building in the background has defined lines)

In order to maintain somewhat perfect exposure of an image, you have to have a balance between shutter speed and aperture size. If you have a big hole, the shutter doesn't have to be open as long. If you have a really small hole, you'll need the shutter open longer. The nice thing about aperture priority is you have the ability to play with the creative aspects of DOF without having to really figure out a balanced shutter speed. Let the camera do it for you. This way, you have the best of both worlds, some creative decision with some of the ease of automation.