Tip of the week: Remember how the aperture affects both the exposure and the depth of field within an image. Depth of field is the area of acceptable focus in front and behind the focal plane. In other words, the depth of field will determine how blurry the background and foreground are from the main subject. Shallow depth of field images are used to create separation from the background to highlight the main subject. This technique is used a lot in portraiture. Images with a lot of depth of field are used to showcase the entire image from foreground to background. Images with maximum amount of depth of field are also used to help abstract an image due to the relative lack of apparent focal plane. This affect will help flatten the image and minimize dimensionality within the frame. Many landscape images are taken to show the maximum amount of depth of field.

The aperture is represented by a f/number. The aperture is calculated by dividing the focal length by the maximum diameter of the entrance pupil of the lens. So a 300mm lens with a maximum diameter of 75mm would be an f/4 lens. Apertures that let in the most amount of light have lower numbers (ex: f/4 lets in more light than f/5.6, however f/4 lets in less light than f/2.8). Many people have a hard time thinking about the lower numbers letting in more light, however it can be easier to understand if you realize that all of the apertures are fractions (much like shutter speeds). 1/4 will let in more light than 1/5.6. Larger apertures (smaller numbers) allow for shallow depth of field while smaller apertures (bigger numbers) allow for deep depth of field.