A remote lens is in the photograph , a lens of long focal length with a simple lens system (often a triplet or achromatic ), which in the overall length approximately equal to the focal length. A telephoto lens, on the other hand, has a shorter overall length due to the use of a rear diffusion element that acts like an integrated teleconverter .
Long-distance lenses can be produced very inexpensively with moderate light intensity and certainly deliver an appealing image quality. However, bright variants are not offered because the imaging errors of the simple optics increase sharply with large initial openings and the construction would be very unwieldy.
See also: camera