Depth of field

Optics and Depth of Field

Your Lens

•Your lens is made up of curved glass that is moved when you focus and zoom

Focal Length

• Focal length refers to the strength of magnification by a lens

24mm

50mm

200mm

800mm

Focal Length and Angle of View

• The Shorter the Focal Length the wider the angle of view

Other features of focal length

• Short Focal length = wide angle– Wide angle lenses tend to distort objects

especially if they are close to the lens

• Long focal length tends to compression image

Wide Angle Distortion

Wide Angle Distortion

Long Focal Length/Telephoto Compression

Telephoto Compression

Special Lenses

Tilt Shift Lens

Tilt Shift

Tilt Shift

Fisheye

Fisheye

Depth of Field

• The portion of a scene that appears sharp in the image

• A lens can precisely focus at only one distance, but the decrease in sharpness is gradual on either side of the focused distance

• Not easily perceived by the human eye

Long/Deep Depth of Field Shallow Depth of Field

Depth of Field is Controlled by Three Things

1. Aperture

2. Focal Length-zoom

3. Closeness of subject to camera

Controlling Depth of Field with Aperture

• A low aperture (1.8 to 5.6) gives you low.short/shallow depth of field

• A high aperture (11-32) gives you a long/deep depth of field

F 3.5

F 22

Controlling Depth of Field with Focal Length

• Longer lenses tend to give you a shorter depth of field resulting in blurrier backgrounds

• Wider lenses are better at keeping more depth in focus

Controlling Depth of Field with Proximity to Subject

• Similarly, the closer you are to the object the less depth of field will be present

• This is the same idea as focal length