Aperture Priority Exercise

Exercise:

Depth of Field (DOF) 

This exercise will help you understand how to use the aperture priority mode (Av) on your camera to achieve the desired DOF. A tripod is recommended for this exercise. Set your camera to Av and do the following;

1. Find a scene with interesting subjects at many distances from you. Photograph the scene with different apertures (in the Av mode the camera will keep the photo exposed correctly by changing shutter speed).  Look to see the difference in the depth of field in each image.
2. Find a small subject that stands against a background a few meters away, like a flower. Try adjusting the aperture to isolate the subject from the background with depth of field.
3. Find a view. Try and photograph a vista with something in the foreground, such as a rock at a lookout. Try and adjust the aperture to keep the whole photo in focus.

Use wide angle lenses combined with small apertures to create
images with lots of depth of field. Telephoto lenses with large apertures have very
shallow depth of field. Shallow DoF is used for portraits to separate
the subject from the background.

TIP: If you’re creating portraits, and you want to blur the backgrounds even more, use a 50mm f/1.4 or a 50mm f/1.8 lens. These lenses are commonly referred to as “Portrait” lenses because of the natural perspective and ability to control depth-of-field for selective focus.