A telephoto lens, used for optical zoom on an SLR camera.
Zoom is one of the most common features that an SLR camera possesses. Zoom allows the subject of the photograph to be magnified without actually moving closer to the subject.
Lenses
A lens works by gathering light and refracting it onto a single spot, typically film or an image sensor. An SLR camera can contain a variety of internal lenses that aid in the refracting process.
Optical Zoom
By manipulating the distance between the internal lenses of a camera, a zoom effect is achieved. The movement of these lenses causes zoom in one of two ways: by refracting the light differently, or by moving the lens closer to the subject.
Telephoto Lenses
A telephoto lens is a type of "zoom lens." It works by refracting the incoming light differently as the lens is zoomed. However, these lenses can cause a distorted perspective.
Resolution
Zoom has absolutely no bearing on a camera's resolution. This is a common misconception. A digital camera's resolution is based on its megapixel count.
Optical vs. Digital Zoom
Optical zoom works by increasing the image size before the image is captured. Digital zoom works by electronically enlarging the final image. Therefore, optical zoom is the preferred method of camera zoom.
Tags: camera resolution, closer subject, internal lenses, lens works, light differently, telephoto lens