Ways to Control Depth of Field

150mm	180mm
S6	Canon 11-24mm
Q	Sigma 12-24mm

@ Bastian Kratzke

When aiming for a desired depth of field for a given scene, there are three main technical considerations:

Aperture

The smaller the aperture (higher ‘F’ number), the larger the depth of field. The larger the aperture (lower ‘F’ number), the smaller the depth of field. Every lens has an optimal aperture range that gives the sharpest image. Generally speaking, apertures smaller than F16 may give rise to a degree of image blurring due to ‘diffraction and apertures close to the lens’ widest aperture may produce softer images.

Focal length

The longer the focal length, the more restrictive depth of field becomes. The shorter (wider) the focal length, the more generous depth of field becomes.

Focal distance

This distance from the camera at which optimal focus is centred upon. There will be an area in the scene closer to the camera and further away from the camera where focus will still be in tact (though not necessarily as sharp as at the exact focal distance). This ‘focal plane’ is an important consideration for discussing the concept of ‘hyperfocal distance’.

Hyperfocal distance

Hyperfocal distance is the minimum distance from the camera at any given aperture, where objects will appear in ‘acceptable’ focus even at infinity. It is dependent camera type, aperture and focal length. Once you know the hyperfocal distance, the near point at which objects will remain in focus is half of this distance. Let’s go through an example:

At F11 (a common landscape photographer’s aperture), the hyperfocal distance for a Full Frame camera sensor is 80cm.
Therefore, if you set your camera’s focal distance at 80cm, all elements in your scene will be in focus if within 40cm (half the hyperfocal distance) to infinity.