Camera Lens Mug

Camera Lens Mug

The history of the photographic camera lens began with the Wollaston Meniscus. The single element concavo-convex Meniscus was invented in 1804 by William Hyde Wollaston (UK). It was first used for eyeglasses. (Hyperopic readers may wish to examine their spectacles now.) It was the first reasonably sharp over a wide field (about 50° at f/16) lens. Wollaston fitted it to an artist's aid camera obscura in 1812.

A camera lens were to be constructed from a single lens of 200 mm focal length, then when the lens is focused on an object at infinity, the lens will be 200 mm away from the focal plane where the film or sensor is. The centre of the lens is referred to as the optical centre of the lens. Even constructing the lens out of several elements to minimize aberrations, will still have the optical centre within the construction.

A varifocal lens is a camera lens with variable focal length in which focus changes as focal length (and magnification) changes, as compared to parfocal ("true") zoom lens, which remains in focus as the lens zooms (focal length and magnification change). Many so-called "zoom" lenses, particularly in the case of fixed lens cameras, are actually varifocal lenses.

Camera Lens Mug