The main shooting mode dial on your camera has the letter(s) A or Av (depending on the camera system that you wield). As you probably know by now, this stands for the Aperture Priority mode. Aperture priority mode gives you the creative control over the aperture you select for your images. Aperture, as you must be aware off, refers to the small opening at the front of the lens through which light gets inside a camera. It is often compared with the pupil of the eye. It is an appropriate comparison. Aperture is expressed in f-stops. It is written like this – f/2, f/2.8, f/4, f/5.6 and so on. The numerator is the focal length of a lens and the denominator is the diameter of the opening of the lens.
The size of the opening (aperture) controls what is known in photography – the Depth of Field. You may have already heard about it. If you haven’t, it is referred as the extent of an image that appears acceptably sharp. Depth of Field (DoF) can be either shallow or large. Both have creative uses. In this article we shall be looking at a few situations and discuss the appropriateness of the aperture value used in such situations and in the process discuss about the creative uses of depth of field.
As has already been mentioned DoF varies according to the size of the aperture. But there is a small twist in the tale. Smaller aperture creates larger Depth of Field and conversely larger aperture creates shallow (smaller) Depth of Field. Here is an example.
In the image above, however, the f-stop used was f/5.6. This is neither a small f-stop nor a big one. Somewhere in the middle. What I have done is while using an aperture of f/5.6 I have also stepped in close to my subject. In doing so I have changed the ratio of distance between the subject and my lens and with that of the subject and the background. This is another critical factor for producing a shallow DoF. Step in close to your subject to blur the background (and foreground). If I had used a wider aperture like f/3.5 I would have been able to blur the foreground / background even further.
The reason I wanted to blur the background was so that I could isolate the subject against a background that was not very attractive. For those who are interested, the image was shot in Raghurajpur – a heritage village in Orissa famous for a style of painting known as Patachitra.
Speaking of blurring here’s is an example of how a small aperture can be used to selectively emphasize a specific area of a larger scene.
You don’t always have to isolate a subject against the background. Sometimes the entire frame deserves your utmost attention and that means you need to use an aperture that produces a large DoF. One area where a large DoF is frequently used is in landscapes. Vast sweeping meadows, seascapes and even cityscapes are some of the areas where large DoFs are regularly in use. But there are uses beyond these as well.
The image above was shot at f/6.3. This is a small enough aperture to create a sharp photo of a wall painting at the aforementioned village. This wall painting style typical of Orissa has been passed down from one generation to another for hundreds of years.
Another example of a vast Depth of Field when you need it to highlight something in its entirety in front of you. This is an image painted on specially made (by hand) fabric and using colors which are also produced from natural ingredients. This image captures the beauty of the artist’s vision reproduced such masterfully over countless painstaking hours. A typical painting like this size roughly 2.5’ by 1.5’ takes somewhere between 1-2 months to produce.
DoF is an interesting attribute that you can use creatively in your photography and to accentuate the subject of your photo. There is no given rule as to when one should use a small or a large DoF. It all depends on the subject and your vision as to how you wish to represent what you see in front of you.