Aperture Priority Mode - Why use it?
Lots of folks ask me how they can go about taking better photos.They ask questions like, how can I prevent my photos from being blurry, or how do you make the background blurry, but not everything else?
What I usually tell people is the first thing to do is to take their camera out of auto mode and to try out some of the more manual modes on their cameras, to really take the time and learn what they do, how they affect the picture. The mode that I use probably the most often is Aperture Priority. With aperture priority, you set the aperture, and your camera will set whatever shutter speed is appropriate given the lighting conditions, and what ISO the camera is set to.
In order to understand what aperture priority does, you have to understand what aperture is and how it relates to photography.
In its most basic sense, aperture is the control in your camera lens that determines how much light reaches the image sensor or film negative. Cameras utilize a diaphragm which much like the iris in your eye, opens and closes ranging from a large to very small hole. The size of this opening is measured as an f-number, or f-stop. A lower number f-stop is a larger opening, and lets in more light. A higher number f-stop is a smaller opening, and lets in less light. A good way to remember this is that a larger f-stop stops more light, while a smaller f-stop stops less light. A typical f-stop range is from f/2.8 through f/16.
Now how does this affect your photos? One very important thing that aperture controls, is how much of your photo is in focus. Let’s pretend that we are are looking out at beautiful landscape and want to keep everything in focus. To achieve this you would use a very high aperture number, like f/11 or f/16, or maybe even f/22. Or lets say you’re taking a portrait of your sweetie, and want only his or her face to be in focus, and want the background to be blurry? To do this, you’ll want to use a lower f-stop, like f/4 or f2.8. One thing to be aware of when you want to blur the background, is that you want your subject to be a good distance away from whats in the background. The distance will vary depending on what f-stop you are using.
I would say that I shoot aperture priority about 80% of the time. It gives me the most control over how I want my photos to look. When I’m shooting in low light conditions, for example indoors, or at night. I like to use the larger apertures in order to allow as much light as possible in to the camera in order to take a photo. However if I’m shooting something outdoors in sunny weather, I’ll use a very small aperture to limit the amount of light, to prevent the picture from being too bright, and to make sure everything is in focus.
I encourage you dear reader, to go out and play with aperture priority. Go make some great photos where you select different aperture settings and see what you get. You may make mistakes, or may not like what you get, but the more you shoot, the more you learn.
This was shot in Aperture Priority Mode at f/4 at a shutter speed of 1/800th of a second. The trees behind the butterflies were 15 feet away.
This landscape shot of Yosemite valley was shot at f/11 with a shutter speed of 1/80th of a second in order to get a deep depth of field.