Friday, 12 January 2007

Create A Shallow Depth Of Field (DoF) Or Blurred Background In Your Photo

A shallow Depth Of Field describes that only objects within a certain distance (range) are in-focus and appear sharp in the photo. Objects more far away (or closer) will be out-of-focus/ blurred. This effect can be used to emphasise an in-focus (sharp) foreground object or person against a blurred background. Or to create an “artistic” image that draws the attention of the viewer to a certain sharp (in focus) part of the photo. The technique is often used in portrait and macro (eg flowers) photography.

The Depth Of Field is defined as range (in cm or meter) that will be recorded sharp. How shallow (long, wide, deep, large) the depth of field is, depends on

  • Aperture Setting
  • Focal Length
  • Distance to Subject

The rules are
  • The wider your lens opens when taking the photo (=lower f-stop number = larger aperture) the smaller the depth of field will be
  • With greater focal length the depth of field will become smaller
  • With greater subject distance the depth of field will become lager

Of cause there is an exact science behind it and you can calculate the distances based on focal length and aperture. However, I recommend to just try it out and develop a feel for it. But here is the calculator:

Switch the camera to “Av mode” to manual control the aperture (f-stop) on your camera. Take the same scene with the lowest and the highest f-stop number to see the difference. Remember that you will need objects with a different distance to the camera. This will not work when shooting a wall or any flat object ;-) Also “zoom-in” (=long focal length) to increase the effect.

Example below: Look at the label of the middle and last wine bottle. The left wine bottle is approx. 1.5m away from the camera and each bottle – from left to right – about 15cm from each other.

200mm, f5.6

200mm, f11

200mm, f32

Also this effect is harder to achieve with point-and-shoot cameras (= P&S = small compact digitals) due to the technology used. The smaller sensor size compared to SLR cameras creates larger Depth Of Field. Therefore use the maximum optical zoom when trying this out.

The distance between foreground and background is essential. If you want to take a portrait with a blurred background, have a significant distance between the person and the background.


Paul said...

Good post - very informative.

Please feel free to post to

Mark said...

good advise, ty!