telephoto lens

from the GNU version of the Collaborative International Dictionary of English.

• noun a special compound camera lens with a long effective focal length but used in a camera with a short focal length, allowing large images to be obtained of distant objects when used in a camera in place of an ordinary lens; -- called also telephotographic lens.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun photography A lens having a long focal length which produces a magnified view of distant objects.
• noun photography A lens which produces a magnified view of distant objects and which is sufficiently compact to have a physical length shorter than its focal length (as distinct from a long-focus lens).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a camera lens that magnifies the image