Wide-angle lens

In photography and cinematography, a wide-angle lens refers to a lens whose focal length is substantially smaller than the focal length of a normal lens for a given film plane. This type of lens allows more of the scene to be included in the photograph, 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 emphasise 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 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, or a wide field of view.

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".[2]

Canon 17-40 f4 L lens
One of Canon's most-popular wide-angle lenses – 17-40 mm f/4 L retrofocus zoom lens.
Irix Blackstone 15 mm f-2.4
Irix Blackstone 15 mm, a modern wide-angle lens for full-frame cameras.
Focal length
How focal length affects photograph composition. Three images depict the same two objects, kept in the same positions. By changing focal length and adjusting the camera's distance from the pink bottle, it remains the same size in the image, while the blue bottle's size appears to dramatically change. Also note that at small focal lengths, more of the scene is included.

Angle of view

A lens is considered wide-angle when it covers the angle of view between 64° and 84° which in return translates to 35–24mm lens in 35mm film format.

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. Wider lenses tend to magnify 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 backwards 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 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 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 for a full-frame 35 mm camera 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 here.

Ultra wide-angle lenses that do not produce a rectilinear image (i.e., exhibit barrel distortion) are called fisheye lenses. Common focal lengths for these in a 35 mm camera are 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

Full-frame vs APS-C
Field of view in APS-sized digital cameras is the same as that of a longer lens, increased by crop factor, on a full-frame 35 mm format camera.

As of 2015, many interchangeable-lens digital cameras have image sensors that are smaller than the film format of full-frame 35 mm cameras.[a] 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 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. As 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

Symetrical
Cross-section of a typical short-focus wide-angle lens.
Angenieux
Cross-section of a typical retrofocus wide-angle lens.

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 view cameras and rangefinder 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.

Lens wideangle
Effective focal length is measured from the sensor to where the light cone going to the sensor is the same size as the lens front opening.

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.

See also

Notes

  1. ^ 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. 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.

References

  1. ^ "Using wide angle lenses". Cambridge in Colour. Retrieved 27 December 2011.
  2. ^ Anton Wilson, Anton Wilson's Cinema Workshop, American Cinematographer, 2004 (Page 100) ISBN 0-935578-26-9

External links

35 mm equivalent focal length

In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is useful because most photographers experienced with interchangeable lenses are most familiar with the 35 mm film format.

On any 35 mm film camera, a 28 mm lens is a wide-angle lens, and a 200 mm lens is a long-focus lens. However, now that digital cameras have mostly replaced 35 mm cameras, there is no uniform relation between the focal length of a lens and the angle of view, since the size of the camera sensor also determines angle of view, and sensor size is not standardized as film size was. The 35 mm equivalent focal length of a particular lens–sensor combination is the focal length that one would need for a 35 mm film camera to obtain the same angle of view.

Most commonly, the 35 mm equivalent focal length is based on equal diagonal angle of view. This definition also in the CIPA guideline DCG-001. Alternatively, it may sometimes be based on horizontal angle of view. Since 35 mm film is normally used for images with an aspect ratio (width-to-height ratio) of 3:2, while many digital cameras have a 4:3 aspect ratio, which have different diagonal-to-width ratios, these two definitions are often not equivalent.

Angénieux retrofocus

The Angénieux retrofocus photographic lens is a wide-angle lens design that uses an inverted telephoto configuration. The popularity of this lens design made the name retrofocus synonymous with this type of lens. The Angénieux retrofocus for still cameras was introduced in France in 1950 by Pierre Angénieux.

Banquet photography

Banquet photography is the photography of large groups of people, typically in a banquet setting such as a hotel or club banquet room, with the objective of commemorating an event. Clubs, associations, unions, circuses and debutante balls have all been captured by banquet photographers.

A banquet photograph is usually taken in black and white with a large format camera, with a wide angle lens, from a high angle to ensure that each person is in focus while seated at their table. Large cameras such as a 12×20 view camera or a panoramic camera were used. The defining characteristic of a banquet photograph is the depth of focus and detail and clarity of the image.

Banquet photography was most popular in the 1890s, and had mostly waned by the 1970s. In part its decline is owed to the difficult technical aspects of producing quality banquet photos, the difficulty of printing such large negatives, and the expense and size of the equipment needed. Today, though hard to find, there are a handful of photographers still shooting banquet photos with flashbulbs and large format film cameras.

Canon EF-M 11–22mm lens

The Canon EF-M 11-22mm f/4-5.6 IS STM is an interchangeable wide angle lens for the Canon EOS M system of mirrorless cameras. It was announced by Canon Inc. on June 6, 2013. This lens was for long time not available from Canon USA, but it is since 2015.

Canon EF-M 18–55mm lens

The Canon EF-M 18-55mm f/3.5-5.6 IS STM is an interchangeable wide angle lens for the Canon EOS M system of mirrorless cameras. It was announced by Canon Inc. on June 22nd 2012. It is the kit lens of the Canon EOS M camera. The current EOS M3 camera is only available with this kit lens. This lens was for long time not available from Canon USA, but it is since 2015.

Canon EF-M 22mm lens

The Canon EF-M 22mm f/2 STM is an interchangeable wide-angle lens announced by Canon on July 23, 2012. It was not available from Canon USA until the 27th of August 2015, but it was available as part of a kit with the EOS M in 2012.As a pancake lens, it is the physically shortest Canon lens available on the EF-M mount. Its 22mm focal length has the same field of view on an EOS M-series camera as a 35mm lens on a full-frame camera.

Canon EF 11–24mm lens

The EF 11–24 mm lens is a professional wide-angle lens made by Canon Inc. It was announced on February 5, 2015, and at that time was the widest rectilinear lens ever made for the 35 mm format in either its film or digital versions.The lens has an EF mount to work with the EOS line of cameras. Other than the front element, it is sealed against dust and water, and features a diaphragm which remains nearly circular. It produces minimally distorted images.

Canon EF 20–35mm lens

The EF 20–35mm lens is a wide-angle lens made by Canon Inc., with an EF mount. There are two models, an L-series f/2.8L and a consumer-grade f/3.5–4.5.

Kodak EasyShare V570

The Kodak EasyShare V570 was a 5-megapixel digital camera manufactured by Eastman Kodak. Announced on January 2, 2006, it was an upper-end model in the consumer price range, advertised at $400 in the United States in January 2006. It had an innovative dual lens system, combining two periscopic groups each with its own sensor: one very wide angle equivalent to a 23 mm in 135 format and a 3X zoom equivalent to a 39–117 mm, totalizing a virtual 5X zoom, with a step between 23 and 39 mm. It is the first dual lens digital camera. The model won a gold medal in the 2006 Industrial Design Excellence Awards.There were two other models in Kodak's line of dual lens cameras that were announced shortly after the introduction of the Easyshare V570: the Easyshare V610, which was announced on April 25, 2006 and the Easyshare V705, which was announced on August 8, 2006.The Easyshare V610 was a 6-megapixel, Bluetooth-enabled, dual lens camera that forged the fixed focus 23 mm wide angle lens of the V570 and V705 for a 38-114mm lens. Unlike the V570, it did not include a dock.

The Easyshare V705 was a 7.1-megapixel camera that was offered in 3 body colors - black, silver, and pink. It also did not include a dock.

Long-focus lens

In photography, a long-focus lens is a camera lens which has a focal length that is longer than the diagonal measure of the film or sensor that receives its image.

It is used to make distant objects appear magnified with magnification increasing as longer focal length lenses are used. A long-focus lens is one of three basic photographic lens types classified by relative focal length, the other two being a normal lens and a wide-angle lens.

As with other types of camera lenses, the focal length is usually expressed in a millimeter value written on the lens, for example: a 500 mm lens. The most common type of long-focus lens is the telephoto lens, which incorporate a special lens group known as a telephoto group to make the physical length of the lens shorter than the focal length.

Oppo R11

The OPPO R11 is a phablet smartphone based on Android 7.1, which was unveiled on 10 June 2017. The model has a front camera of 20 MP and a dual rear primary camera that has a 20 MP telephoto lens and a 16 MP wide-angle lens.

Panasonic Lumix DMC-LZ20

Panasonic Lumix DMC-LZ20 is a digital camera by Panasonic Lumix. The highest-resolution pictures it records is 16.1 megapixels, through its 25mm Wide-Angle Lens.

Panasonic Lumix DMC-LZ30

Panasonic Lumix DMC-LZ30 is a digital camera by Panasonic Lumix. The highest-resolution pictures it records is 16.1 megapixels, through its 25mm Wide-Angle Lens.

Perspective distortion (photography)

In photography and cinematography, perspective distortion is a warping or transformation of an object and its surrounding area that differs significantly from what the object would look like with a normal focal length, due to the relative scale of nearby and distant features. Perspective distortion is determined by the relative distances at which the image is captured and viewed, and is due to the angle of view of the image (as captured) being either wider or narrower than the angle of view at which the image is viewed, hence the apparent relative distances differing from what is expected. Related to this concept is axial magnification -- the perceived depth of objects at a given magnification.

Perspective distortion takes two forms: extension distortion and compression distortion, also called wide-angle distortion and long-lens or telephoto distortion, when talking about images with the same field size. Extension or wide-angle distortion can be seen in images shot from close using a wide-angle lens (with an angle of view wider than a normal lens). Objects close to the lens appear abnormally large relative to more distant objects, and distant objects appear abnormally small and hence farther away – distances are extended. Compression, long-lens, or telephoto distortion can be seen in images shot from a distance using a long focus lens or the more common telephoto sub-type (with an angle of view narrower than a normal lens). Distant objects look approximately the same size – closer objects are abnormally small, and more distant objects are abnormally large, and hence the viewer cannot discern relative distances between distant objects – distances are compressed.

Note that linear perspective changes are caused by distance, not by the lens per se – two shots of the same scene from the same distance will exhibit identical perspective geometry, regardless of lens used. However, since wide-angle lenses have a wider field of view, they are generally used from closer, while telephoto lenses have a narrower field of view and are generally used from farther away. For example, if standing at a distance so that a normal lens captures someone's face, a shot with a wide-angle lens or telephoto lens from the same distance will have exactly the same linear perspective geometry on the face, though the wide-angle lens may fit the entire body into the shot, while the telephoto lens captures only the nose. However, crops of these three images with the same coverage will yield the same perspective distortion – the nose will look the same in all three. Conversely, if all three lenses are used from distances such that the face fills the field, the wide-angle will be used from closer, making the nose larger compared to the rest of the photo, and the telephoto will be used from farther, making the nose smaller compared to the rest of the photo.

Outside photography, extension distortion is familiar to many through side-view mirrors (see "objects in mirror are closer than they appear") and peepholes, though these often use a fisheye lens, exhibiting different distortion. Compression distortion is most familiar in looking through binoculars or telescopes, as in telescopic sights, while a similar effect is seen in fixed-slit strip photography, notably a photo finish, where all capture is parallel to the capture, completely eliminating perspective (a side view).

Quest for Ratings

"Quest for Ratings" is the eleventh episode in the eighth season of the American animated television series South Park. The 122nd episode of the series overall, it originally aired on Comedy Central in the United States on November 17, 2004.

In the episode, the boys produce their own morning news show on the school's closed-circuit television station and are immediately caught up in an intense competition for ratings.

Sigma 20mm F1.4 DG HSM Art

The Sigma 20mm F1.4 DG HSM Art is an interchangeable wide angle lens announced by Sigma Corporation on October 16, 2015.

Sigma 24mm F1.4 DG HSM Art

The Sigma 24mm F1.4 DG HSM Art is an interchangeable wide angle lens for full frame cameras. It was announced by Sigma Corporation on February 10, 2015.

A review by LensTip gave the lens high praise in all aspects except coma, vignetting and autofocus speed, while Amateur Photographer highlighted its sharpness and "smooth, attractive rendition of out-of-focus regions".

Sigma 24mm f/1.8 EX DG lens

The Sigma 24mm f/1.8 EX DG is wide-angle lens which features a fast f/1.8 maximum aperture for use in low-light situations, and macro focusing capability to a reproduction ratio of 1:2.7. It uses aspherical lens elements. Though intended for 35mm film and full-frame digital SLRs, this lens is available for several makes of APS-C digital SLR cameras, where the angle of view is similar to a moderate wide-angle lens (in the 35mm-40mm range, depending on the size of the D-SLR sensor).

This lens is capable of macro photography, with minimum focusing down to 18 cm/7.1" (reproduction ratio 1:2.7). It incorporates a floating focus system in order to minimize distortion, spherical aberration and astigmatism, and provides high performance at all shooting distances. The high reproduction ratio and wide angle of view allow capturing high quality images not only of a subject but also the surrounding scenery.

The Lens was introduced in 2001.

Ultra wide angle lens

An ultra wide-angle lens is a lens whose focal length is shorter than the short side of film or sensor.Thus the term denotes a different range of lenses, relative to the size of the sensor in the camera in question.

For 1" any 9mm or shorter is considered ultra wide angle.For 4/3" any 12mm or shorter lens is ultra wide angle.For APS-C any lens shorter than 15 mm.

For 35mm film or full-frame sensor any lens shorter than 24 mm

For 6x4.5 cm any lens shorter than 41 mm

For 6x6 cm and 6x7 cm any lens shorter than 56 mm

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