Normal lenses

A "normal" (or standard) lens is one that reproduces a field of view that generally looks natural to a human eye. In other words, the subject appears the same size when viewed through the lens as when viewed with the naked eye, and there is no apparent image distortion: normal lenses are not wide-angle or telephoto. For a 35mm film camera, the "normal" lens adopted by most manufacturers had a focal length of 50mm.

Wide angle lenses

A wide angle lens has a focal length substantially smaller than that of a normal lens. A typical 35mm film camera wide angle lens most commonly had a focal length of 35mm or 28mm. This type of lens allows more of the scene to be included in the photograph, but does much more than simulate being further away from the subject.

Wide angle lenses emphasize the difference in size and distance between objects. Nearby objects appear somewhat larger, and distant objects appear comparatively smaller. This exaggeration of relative sizes can be used to make foreground objects more prominent and eye-catching, while capturing expansive backgrounds.

One consequence of using a wide-angle lens is to emphasize perspective distortion: parallel lines converge more. For example, buildings may appear bent or fall back when the camera is pointed up from the ground.

Wide angle lenses have a great "depth of field". Briefly it means that they allow more of the scene to have a sharp focus: when the focus is on the near subject, the background will probably be in focus too.

The wide-angle zoom lens setting is good for architectural, interior, and landscape photography - any scene where a large space needs to be captured. They are not intended as an alternative to get away from the subject.

Telephoto lenses

Telephoto lenses are sometimes divided into two subtypes: medium telephoto (85mm to 135mm for 35mm film format) and super telephoto (more than 300mm in 35mm film format).

Telephoto lenses are best known for making distant objects appear magnified. In 35mm photography (where 50mm is the standard focal length), a 100mm lens would make the subject appear twice as big; a 200mm lens would make it look four times bigger etc.

Obviously, telephoto lenses have an application for getting closer to a subject than is physically possible (such as wildlife photography with super telephoto lenses), but other optical effects do occur, which are opposite to those of a wide-angle lens.

Long lenses seem to compress the distance between objects (make them appear closer together). They tend to better preserve parallels (not make linear objects appear to tilt or bend).

Telephoto lenses also have a shallower depth of field, so when you focus on the subject or in the foreground, background blur occurs. Therefore, long lenses make it easier to blur the background (blur the background in an image to help the subject stand out).

In addition to getting close, an important application for medium telephoto lenses is portrait photography.

Portrait glasses

The lenses used in portrait photography are usually fast (that is, they have a large aperture), medium telephoto lenses with a focal length of 85mm to 135mm.

This focal length lens provides the most flattering perspective distortion for head and shoulder portraits. Wider angle lenses require closer portraits, and the consequent perspective distortion makes noses relatively larger. Portrait lenses do the opposite.

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