This post is concerned with depth of field, illustrated by the image of my water bottle and some scrunched up paper. Shallow depth of field holds the main object (in the foreground) in focus, while blurring the background. It’s achieved by using a large aperture (i.e., a small f-stop) and placing the focal object quite close to the camera.
My water bottle was shot at 1/640th of a second at f 3.5 with an ISO of 400. The focal length was 18mm.
This picture of some scrunched up paper provides an even better image of the effects of a shallow depth of field. The two pieces of paper were approximately 20 cm apart. The image was shot with a longer focal length (52mm) than the image of my water bottle (18mm). It was shot at 1/160th of a second, f 5.0 and an ISO of 400.
As is apparent from both images, the immediate foreground is also blurred, fitting the 1/3 in front 2/3 behind notion of focus.
The Depth of Field Contact Sheet is a collection of photographs taken with different f stops (running from the lowest f stop I could use on my camera and increasing every f stop through to the highest f stop I could access. As is apparent from the thumbnails, the depth of field changes as a aperture changes.