Wide-angle Lens
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photography Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is empl ...
and
cinematography Cinematography () is the art of motion picture (and more recently, electronic video camera) photography. Cinematographers use a lens (optics), lens to focus reflected light from objects into a real image that is transferred to some image sen ...
, a wide-angle lens is a
lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
covering a large
angle of view In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term '' field of view''. It is important to distinguish the angle of view from the ...
. Conversely, its
focal length The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Converge ...
is substantially smaller than that of a normal lens for a given film plane. This type of lens allows more of the scene to be included in the
photograph A photograph (also known as a photo, or more generically referred to as an ''image'' or ''picture'') is an image created by light falling on a photosensitivity, photosensitive surface, usually photographic film or an electronic image sensor. Th ...
, 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. A wide-angle lens is also one that projects a substantially larger image circle than would be typical for a standard design lens of the same focal length. This large image circle enables either large tilt & shift movements with a
view camera A view camera is a large format, large-format camera in which the large format lens, lens forms an erect image, inverted image on a ground glass, ground-glass screen directly at the film plane. The image is viewed, composed, and focused, then the ...
. By convention, in still photography, the normal lens for a particular format has a focal length approximately equal to the length of the diagonal of the image frame or digital photosensor. In cinematography, a lens of roughly twice the diagonal is considered "normal".Anton Wilson, ''Anton Wilson's Cinema Workshop'', American Cinematographer, 2004 (Page 100)


Characteristics

Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallower
depth of field The depth of field (DOF) is the distance between the nearest and the farthest objects that are in acceptably sharp focus (optics), focus in an image captured with a camera. See also the closely related depth of focus. Factors affecting depth ...
. 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 apparent perspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with a normal 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 the
angle of view In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term '' field of view''. It is important to distinguish the angle of view from the ...
can indirectly distort perspective, changing the apparent relative size of the subject and foreground.


Wide-angle lenses for 35 mm format

For a full-frame 35 mm
camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
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. In 35 mm, an ultra wide-angle lens has a focal length shorter than 24 mm. Common wide-angle lenses for a full-frame 35 mm
camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
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 less rectilinear image at the film plane, though some degree of barrel distortion is not uncommon. Ultra wide-angle lenses that do not produce a rectilinear image (i.e., exhibit barrel distortion) are called
fisheye lens A fisheye lens is an ultra wide angle lens, ultra wide-angle lens that produces strong Distortion (optics), visual distortion intended to create a wide panorama, panoramic or Sphere#Hemisphere, hemispherical image. Fisheye lenses achieve extremel ...
es. Common focal lengths for these in a 35 mm
camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
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.


Digital camera considerations

, many interchangeable-lens digital cameras have
image sensor An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves (as they refraction, pass through or reflection (physics), reflect off objects) into s ...
s that are smaller than the film format of full-frame 35 mm cameras.The few exceptions include the Canon EOS-1D X, EOS 5DS/5DS R, EOS 5D Mark III and EOS 6D; Nikon's D4S, Df, D810, D750 and D610; and Sony's α99 and α7
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
. Discontinued full-frame cameras include the Canon EOS-1Ds, Canon EOS-1Ds Mark II, Canon EOS-1Ds Mark III, EOS 5D, EOS 5D Mark II, Nikon D4, Nikon D3, Nikon D800, Nikon D700, Nikon D600, Contax N Digital, Sony Alpha 900, Sony Alpha 850, Kodak DCS Pro SLR/c and Kodak DCS Pro SLR/n.
For the most part, the dimensions of these image sensors are similar to the APS-C image frame size, i.e., approximately 24 mm x 16 mm. Therefore, the
angle of view In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term '' field of view''. It is important to distinguish the angle of view from the ...
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 (the Four Thirds and Micro 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 a 35 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.


Construction

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 for single-lens reflex cameras unless they are used with the reflex mirrors locked up. On
large format Large format photography refers to any imaging format of or larger. Large format is larger than "medium format", the or size of Hasselblad, Mamiya, Rollei, Kowa, and Pentax cameras (using 120 film, 120- and 220-roll film), and much la ...
view camera A view camera is a large format, large-format camera in which the large format lens, lens forms an erect image, inverted image on a ground glass, ground-glass screen directly at the film plane. The image is viewed, composed, and focused, then the ...
s and
rangefinder cameras A rangefinder camera is a camera fitted with a rangefinder, typically a split-image rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus. Most var ...
, 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. (See Angénieux 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 for single-lens reflex cameras. The axial adjustment range for focusing Ultra wide angle lenses and some Wide-angle lenses in large 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.


Development

The first wide angle lens was developed in the 1850s by photographer Thomas Sutton. It involved a water filled lens creating panoramic visuals without the use of a rotating body.


See also


Notes


References


External links

*
The physics of Rectilinear and Equidistant wide angle lenses
{{Authority control Photographic lenses Television terminology