a device that enlarges the center portion of the normal frame to fill the whole frame

a group of (A transparent optical device used to converge or diverge transmitted light and to form images) lenses

an additional lens (or lenses) that extends the base focal length of original lens, making distant objects larger

an optical accessory increases the local length of lens it's attached to

a piece of equipment that sits between your camera and the lens

a small lightweight intermediate optic that will increase the magnification of a lens, while reducing its effective aperture

a special lens placed in between camera and camera lens

An optical system used to increase the effective focal length of the lens that is mounted between a camera body and the lens.

A device, used to increase the effective focal length of a lens that consists of optical glass. It is mounted between the camera and the lens and usually comes in two different sizes: 1.4X and 2.0X. A 1.4X teleconverter increases focal length by 1.4 times, while a 2.0X increases focal length by 2.0 times. The aperture of the lens is also increased by the same amount as the focal length is increased. For example, a 2.0X teleconverter increases focal length of a 200mm lens to 400mm; however, the aperture of F/2.8 is decreased to F/5.6.

Also known as extenders, attach between the camera body and the lens to increase the focal length.

A teleconverter is a group of lenses which is mounted between the camera and a photographic lens. Its job is to enlarge the central part of an image obtained by the objective lens. For example a 2× teleconverter enlarges the central 12×18 mm part of an image to the size of 24×36 mm.