The Camera Lens The lens is an essential component of any camera. It is what controls the amount of light let into the camera, the magnification of the image being captured, and the focus distance of the image. There is no major difference in principle between a lens used for a still camera, a video camera, a telescope, a microscope, or other apparatus, but the details of design and construction are different. A lens might be permanently fixed to a camera, or it might be interchangeable with lenses of different focal length, apertures, and other properties. For film, the cameras we will be focusing on have the ability to switch between different lenses. Zoom Lenses The most well-known and used of all lenses. A Zoom lens comes standard on most DSLR cameras. The convenience of variable focal length comes at the cost of image quality, weight, aperture, and autofocus performance. For example, all zoom lenses suffer from at least slight, if not considerable, loss of im...