How to Use Camera Aperture to Blur Backgrounds
One of a photographer's biggest headaches can come from distracting and unruly backgrounds as a result of the wrong camera aperture. You may have the perfect subject or portrait all set up, but find that a tree is growing out of your model's head. One of the best ways to combat this problem - and at the same time create a dramatic effect - is to blur the background using the right aperture setting.
Set Your Camera
Set your camera at "A" or Aperture priority mode. The basic rule here is the wider your aperture or the lower your f-number is, the shallower the depth of field. This will result in a very blurred background, but a sharp subject. In most cameras, the lens aperture range from f/1.8 to f/22. Set your aperture to f/1.8 for the most blurred background effect. Check your shutter speed if this will yield favorable results.
If you find that the image will be over-exposed due to such a wide aperture, adjust accordingly. You will find that up to an aperture setting of f/5.6, you can still achieve a blurred background. It may be a little sharper than images taken with an f/1.8 aperture, but you will still get the results you prefer.