that will be captured (the frame). With all of this riding on the lens, let’s take a more in-depth look at the camera’s eye on the world. Lenses are composed of optical glass that is both concave and convex in shape. The alignment of the glass elements is designed to focus the light coming in from the front of the lens onto the camera sensor. The amount of light that enters the camera is also controlled by the lens, the size of the glass elements, and the aperture mechanism within the lens housing. The quality of the glass used in the lens will also have a direct effect on how well the lens can resolve details and the contrast of the image (the ability to deliver great highlights and shadows). Most lenses now include things like the autofocus motor and, in some cases, an image-stabilization mechanism. There is one other aspect of the camera lens that is often the first consideration of the photographer: lens length. Lenses are typically divided into three or four groups depending on the field of view they deliver. Wide-angle lenses cover a field of view from around 110 degrees to about 60 degrees (Figure 2.5). There is a tendency to get some distortion in your image when using extremely wide-angle lenses. This will be apparent toward the outer edges of the frame. As for which lenses would be considered wide angle, anything 35mm or smaller could be considered wide.
ISO 100 1/80 sec. f/6.3 10–20mm lens
FIGURE 2.5 A very wide-angle lens allowed me to photograph this billboard and include a large amount of the surrounding area.
CHAPTER 2: FIRST THINGS FIRST
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