Aperture Priority

Pentax SF10, Pentax SMC FK 50mm Macro f2.8

Shooting a camera in program or auto mode is the easiest way to take a picture, but getting into some of a cameras slightly more advanced features requires only a little bit of thought and can make your good photography into great photography. On bodies that have this feature, it will generally be found labeled as A or Av on your dial or in the menus. Depending on your model, the aperture settings may be changed on the lens itself, or with newer cameras with a settings dial conveniently placed near where your hand grips while taking a photo. Some cameras will also have this as a “hidden” feature, so if it’s not obvious it will be in your user manual.

Before getting into why you would choose Aperture Priority mode, it’s important to know what aperture is. If you look inside your lens, you will see a series of blades arranged in a circular pattern which open and close to allow light to flow through to create an image. The size of the opening corresponds with an aperture value, or “f” value on the lens. The smaller the f number is, the larger the blades can open and the less time the shutter needs to be open. A larger opening also means a shallower depth of field and creates a blurrier background. To sum it up, small f value means big opening, large f value means small opening. Once the aperture is chosen, the camera decides how fast the shutter should fire based on the light meter readings.

Essentially, aperture priority allows the photographer to control how blurry they want their background to be and isolate the subject they are shooting. When you want increased blurry use a smaller number, using a larger f stop lets more of the image to be in focus. For our trip to Yosemite National Park, I wanted as much of the landscape to be in focus and used the maximum aperture speed for most of my pictures. On the other hand, if I were shooting a senior portrait, I want the subject to be the focus and would want them to be isolated from the background a little. The pictures below of a Lego Minifigure show the difference in background your at different settings. There is a fine balance between too little/too much and just right, this decision making come with experience. By learning to use aperture, you learn why lenses can cost as much as they do, and why people are willing to upgrade once they outgrow the kit lenses they got in the box with their Christmas gifts. Fortunately, lenses that come in kits today are very capable and rarely need to be upgraded for most people using them.

Now for the cons of using aperture priority, and there aren’t many once you get used to it. Many people, myself included, tend to choose to use a larger value than needed. Lenses aren’t their sharpest at the wider end of their capability, and focus can easily be missed when using large lenses like a 50mm f1.2. If you want good isolation, most times a 2.8-5.6 aperture will be sharp where you focus and blurry where you don’t. On the flip side, using a higher number will create sharp images across the entire photo but will need more time for the shutter to be open. This can be troublesome in low light due to most people not being able to hand hold a camera steady below 1/30 second but is easily remedied with a tripod.

Now go out and shoot some photos.

Point and Shoot, or Program Mode