Canon® EOS Digital Photography Photo Workshop

3.2. LEARNING THE BASICS OF LENSES

Camera lenses cost from less than $100 to as much as $6,000 or more. Yet they all basically do the same job: create an image on the digital sensor. As a rule, however, better-quality lenses, such as the 70-200mm f/2.8L used to take the photo shown in 3-3, are more likely to produce higher-quality results. I love the texture and small features of the wall captured so well by this lens. They are only really visible close-up, such as the small plant growing out of it. The graffiti, however, is a bit of an optical illusion, and is best seen by not looking too closely to get the 3-D effect of the face.

For many of you, your experience with lenses may be limited to film or digital cameras with fixed lenses, so the following sections explore some of the characteristics of photographic lenses. This will enable you to better understand how lenses work and which ones might be right for your style of photography.

3.2.1. FOCAL LENGTH AND ANGLE OF VIEW

Usually expressed in millimeters, the focal length of a lens is the distance from its optical center to the image plane (digital sensor), where theoretically it produces the sharpest image. The angle of view of a lens is how much of the scene, side to side and top to bottom, the lens includes in the image. The angle of view of a lens is determined by the size of the film or sensor and the focal length of the lens. So it stands to reason that for a lens projecting a photographic image, the size of the film ...