What Is a Telephoto Lens?
A telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens in a much shorter overall design. A telephoto lens is a lens designed to photograph long distances - an average telephoto lens can be from 70-200 mm or 100-300 mm, some even go up to 500 mm. The advantages are clear when photographing sports or wildlife in which you are unable to get near to your subject.