What is the most common type of zoom lens?

To answer your question, you should know about depth of field first. Depth of field is the distance between the nearest and the farthest object that appear in sharp focus in an image taken by an SLR camera. Elements beyond sharpness are out of focus. The depth of field can be previewed through most cameras’ viewfinder. When to use DOF? One of the most common questions which amateur photographers asked is: Should I blur the background or not? Well, this is quite subjective and it varies according to the photographers’ needs. But it is still something one can control and rather easily. For example, if the photographer wants to capture a beautiful landscape, he should not blur the image; everything should be in focus, i.e the photographer should have the deeper field possible. In this case, the Depth of field (DOF) is extended. On the other hand, if he wants to capture the expression of a smiling face and separate it from an unaesthetic background, he should use a different setting to isolate the face from the background. Then the DOF is shallow. On the following example, the Depth of field is reduced. The purpose is to prompt people to focus on a particular aspect of the object. Aperture An aperture is the diameter of the diaphragm opening which collects light. The larger the opening of the diaphragm, the more the light will reach the image sensor. The larger the aperture, the better the camera will perform in low-light places. Aperture is directly related to the depth of field. Photographers can choose ‘A’ or ‘Av’ on their camera to enable the aperture priority mode. It allows users to choose specific aperture value while the camera automatically enables the matching shutter speed. We will come back to this later. Apertures are expressed as F-stop (f/value). The smaller the value, the larger the aperture (lens opening). For example, F1.8 will let more light in the camera than the F8. However, some digital cameras have fixed-aperture lens. Practically all SLR lenses have the integrated depth of field scale. This scale helps guide the photographer in taking photos more sharply. Aperture and shutter speed are two important words with which they should be acquainted. Factors affecting depth of field With a larger aperture, faster shutter speed can be used to shoot objects. This is because more light should be allowed in the aperture when using fast shutter speed. So, both aperture and shutter speed work simultaneously. The couple Aperture Value and Shutter speed is commonly referred to as the exposure settings. By using a large aperture (smaller f/value), you obtain a shallow depth of field by using a small aperture (larger f/value) you have greater field depth. It is important to note that the available light has an impact on DOF, as shutter speed may not always be as high as necessary to compensate large aperture value. Distance is another factor that should be considered in depth of field. The greater the distance, the greater the depth of field. Close up shots and macro photographs have lesser field depth. This is one of the reasons why some photos go out of focus in the front when shooting the main subject. There are several types of camera lenses such as normal lenses, macro lenses, telephoto lenses, wide lenses among others. The most important thing to know is that long focal length lenses have depth of field which is shallow where as wide angle lenses have greater depth of field. However, by increasing the focal length, the depth of field decreases. Now, you are better equipped in taking professional photos in relation to depth of field!