A-Photo Mag

Like most things in today’s world, there are two approaches to blurring out the background on your photographs - the classic method that is more difficult to master, but more rewarding at the same time; and the modern quick-fix digital method. It is good to be aware of both. But here we shall focus on the classic photographic techniques and leave the digital version to a later tutorial. The reason is, the digital version is a mimicry of the classic, so you would do well to be aware of the camera techniques.

Blurring out an area in front of or behind the subject is a very useful tool when you want to isolate your subject for obvious reasons. You understand how this is done when you understand the depth of field of the lens at the given aperture. As we know, an aperture determines the diameter of lens opening. The greater the aperture, the more light enters the camera and affects exposure. However, exposure is not the only effect of the aperture of a lens. Apertures also have a direct impact on the depth of field of the lens. When you focus on an object using your lens focusing ring (or on auto focus as may be the case), there is an area in front of the subject as well as behind the subject that are both ‘in focus’ up to a point. Objects in front of the subject will gradually fall more out of focus the closer they are to you (and the further they are from the point of focus). This gradual change in the sharpness or ‘unsharpness’ of objects is what we call the depth of field or ‘d.o.f.’ of the lens at the given aperture. When you are able to get your backgrounds (or foregrounds) out of focus at will, you have become a better photographer. But don’t forget to make an appropriate change in shutter speed to compensate for the increased amount (or decreased amount) of light that is allowed to enter the lens, with the change in aperture.

Take for example, the above image. It made a batter photograph to have the background out of focus. For this, the photographer used a large aperture. Another factor which has an impact of depth of field is the focal length of the lens. A longer focal length (’zoomed in’ for the beginners) produces a shallower depth of field. A 300mm telephoto lens was used to photograph the sample image of a bird in the hands of its rescuer. A wide angle lens has the exact opposite affect and produces a larger depth of field - directly proportional to the ‘wideness’ or shorter focal length. So - the shorter the lens focal length the more the depth of field, the longer the focal length the less depth of field. Also - the larger the aperture the less the depth of field, the smaller the aperture…you get the picture. Use focal length and aperture to control your d.o.f.