Why do photos taken at f/2.8 look sharper if the subject is closer?

Brian Says… Sharpness is enhanced when there’s a clear visible comparison with less sharp parts in the same photograph. Depth of field is a function of the aperture, focal length and the subject distance. Increasing the focal length, opening the aperture wider and reducing the subject distance all reduce the depth of field. Many photographers forget about the subject distance element when considering depth of field for their shot.

Working close to the subject means that the part of the frame that would be normally sharp to our eyes is rendered significantly out of focus, and this gives the impression of super sharpness where the exact point of focus is. With a 135mm lens at f/2.8, there is less than one centimetre in front and behind the subject if it’s just 1.5m from the camera. The same lens and aperture used to photograph a subject 15m away, will give 0.8m in front of, and 0.9m behind the point of focus.

To achieve the sharpest looking portraits with a blurred background, just position the person as close to the camera as possible, and as far from the background as possible.

When the subject is further from the camera there’s more depth of field and the fall off between in focus and out of focus is less obvious

Moving in close reduces the amount of depth of field, making the sharp parts clearly defined