Selective Focus is what makes people pop out of photos or the backgrounds recede in a blur. And you make the choice of what pops, what blurs, and what fuzzes over.
Where do you want the viewer to focus their attention - the hedge in the foreground, the man in the middle, or the trees in the distant background? Many professional photographers use the selective focus technique to control the viewer’s attention.
The apertures, called f-stops, are actually fractions. The f-stop ƒ/4, for example, is really ¼ (one fourth). What one fourth of, is a little beyond the scope of this article. Let’s just say that an f-stop is a fraction, ok? (ƒ/4 = 1/4th f8 = 1/8th). Typically these numbers are on the lens, 2.8, 4, 5.6, 8, 11, 16, 22 and so on.
Remember these are actually fractions: 1/2.8, 1/4, 1/5.6, 1/8, 1/11, 1/16 and 1/22. It provides a comparison of how much light each number lets through the lens. Therefore 1/5.6 allows more light through the lens than 1/22.
Here’s the creative part: the smaller the opening (f-stop) in the lens, the less light is allowed in. Therefore, a greater area is in focus from the foreground to the background. If you want to throw most of the background out of focus, use ƒ/5.6 rather than
Today’s digital cameras allow the photographer to vary the aperture, preview the results, then make a decision about it’s effectiveness.
If you want the subject to “pop”, use the larger lens openings, i.e. ƒ/4 or ƒ/5.6. Like a simple sentence, having one distinguishable subject is better.
A smaller aperture (ƒ/16 or ƒ/22) brings the foreground and background into sharper focus or a greater depth of field. It also allows for other compositional techniques to direct the viewer to the main subject of the photo.
Setting your cameras ISO, shutter speed, and aperture provides more than a properly exposed photograph. These are tools you can use to compose and say what you want to say in your photographs.
Experiment using different ƒ-stops. Try setting the camera to the aperture preferred setting. Explore the creative tools available on the camera. If the camera is always set on automatic, it becomes into a very expensive box camera.