Inphotography andcinematography, awide-angle lens is alens covering a largeangle of view.[a] Conversely, itsfocal length is substantially smaller than that of anormal lens for a givenfilm plane. This type of lens allows more of thescene to be included in thephotograph, which is useful in architectural, interior, and landscape photography where the photographer may not be able to move farther from the scene to photograph it.
Another use is where the photographer wishes to emphasize the difference in size or distance between objects in the foreground and the background; nearby objects appear very large and objects at a moderate distance appear small and far away.
This exaggeration of relative size can be used to make foreground objects more prominent and striking, while capturing expansive backgrounds.[1]
A wide-angle lens is also one that projects a substantially largerimage circle than would be typical for a standard design lens of the same focal length. This large image circle enables either largetilt & shift movements with aview camera.
By convention, in still photography, thenormal lens for a particular format has a focal length approximately equal to the length of the diagonal of the image frame ordigital photosensor. In cinematography, a lens of roughly twice the diagonal is considered "normal".[2]
Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallowerdepth of field. Wider lenses tend to magnify the distance between objects while allowing greater depth of field.
Another result of using a wide-angle lens is a greater apparentperspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with anormal lens but converge more due to the wider total field. For example, buildings appear to be falling backward much more severely when the camera is pointed upward from ground level than they would if photographed with a normal lens at the same distance from the subject because more of the subject building is visible in the wide-angle shot.
Because different lenses generally require a different camera–subject distance to preserve the size of a subject, changing theangle of view can indirectlydistort perspective, changing the apparent relative size of the subject and foreground.
For a full-frame35 mmcamera with a 36 mm by 24 mm format, the diagonal measures 43.3 mm, and by custom, the normal lens adopted by most manufacturers is 50 mm. Also by custom, a lens of focal length 35 mm or less is considered wide-angle.
Ultra wide angle lenses have a focal length shorter than the short side of the film or sensor[citation needed]. In 35 mm, an ultra wide-angle lens has a focal length shorter than 24 mm.
Common wide-angle lenses for a full-frame35 mmcamera are 35, 28, 24, 21, 20, 18, and 14 mm, the latter four being ultra-wide.Many of the lenses in this range will produce a more or lessrectilinear image at the film plane, though some degree ofbarrel distortion is not uncommon.
Ultra wide-angle lenses that do not produce a rectilinear image (i.e., exhibit barrel distortion) are calledfisheye lenses. Common focal lengths for these in a 35 mmcamera is 6 to 8 mm (which produce a circular image). Lenses with focal lengths of 8 to 16 mm may be either rectilinear or fisheye designs.
Wide-angle lenses come in both fixed-focal-length and zoom varieties. For 35 mm cameras, lenses producing rectilinear images can be found at focal lengths as short as 8 mm, including zoom lenses with ranges of 2:1 that begin at 12 mm.
As of 2015[update], many interchangeable-lens digital cameras haveimage sensors that are smaller than thefilm format of full-frame 35 mm cameras.[b] For the most part, the dimensions of these image sensors are similar to theAPS-C image frame size, i.e., approximately 24 mm x 16 mm. Therefore, theangle of view for any given focal-length lens will be narrower than it would be in a full-frame camera because the smaller sensor "sees" less of the image projected by the lens. The camera manufacturers provide a crop factor (sometimes called a field-of-view factor or a focal-length multiplier) to show how much smaller the sensor is than a full 35 mm film frame. For example, one common factor is 1.5 (Nikon DX format and some others), although many cameras have crop factors of 1.6 (most Canon DSLRs), 1.7 (the early Sigma DSLRs) and 2 (theFour Thirds andMicro Four Thirds cameras). The 1.5 indicates that the angle of view of a lens on the camera is the same as that of a 1.5 times longer focal length on a35 mm full-frame camera, which explains why the crop factor is also known as a focal-length multiplier. For example, a 28 mm lens on the DSLR (given a crop factor of 1.5) would produce the angle of view of a 42 mm lens on a full-frame camera. So, to determine the focal length of a lens for a digital camera that will give the equivalent angle of view as one on a full-frame camera, the full-frame lens focal length must be divided by the crop factor. For example, to get the equivalent angle of view of a 30 mm lens on a full-frame 35 mm camera, from a digital camera with a 1.5 crop factor, one would use a 20 mm lens.
Lens manufacturers have responded by making wide-angle lenses of much shorter focal lengths for these cameras. In doing this, they limit the diameter of the image projected to slightly more than the diagonal measurement of the photosensor. This gives the designers more flexibility in providing the optical corrections necessary to economically produce high-quality images at these short focal lengths, especially when the lenses are zoom lenses. Examples are 10 mm minimum focal length zoom lenses from several manufacturers. At 10 mm, these lenses provide the angle of view of a 15 mm lens on a full-frame camera when the crop factor is 1.5.
There are two varieties of wide-angle lens: short-focus lenses and retrofocus lenses.Short-focus lenses are generally made up of multiple glass elements whose shapes are more or less symmetrical in front of and behind the diaphragm. As the focal length decreases, the distance of the rear element of the lens from the film plane or digital sensor also decreases.
This makes short-focus wide-angle lenses undesirable forsingle-lens reflex cameras unless they are used with the reflex mirrors locked up. Onlarge formatview cameras andrangefinder cameras, short-focus lenses are widely used because they give less distortion than the retrofocus design and there is no need for a long back focal distance.
The retrofocus lens solves this proximity problem through an asymmetrical design that allows the rear element to be farther away from the film plane than its effective focal length would suggest. (SeeAngénieux retrofocus.)
For example, it is not uncommon for the rear element of a retrofocus lens of 18 mm to be more than 25 mm from the film plane. This makes it possible to design wide-angle lenses forsingle-lens reflex cameras.
The axial adjustment range for focusingUltra wide angle lenses and some Wide-angle lenses inlarge format cameras is usually very small.Some manufacturers (e.g.Linhof) have offered special focusing lens mounts, so-called 'wide-angle focusing devices' for their cameras that allow the lens to be focused precisely without moving the entire front standard.
The first wide angle lens was developed in the 1850s by photographerThomas Sutton. It involved a water filled lens creating panoramic visuals without the use of a rotating body.[3]
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