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A lens flare happens when light is
scattered Scattered may refer to: Music * ''Scattered'' (album), a 2010 album by The Handsome Family * "Scattered" (The Kinks song), 1993 * "Scattered", a song by Ace Young * "Scattered", a song by Lauren Jauregui * "Scattered", a song by Green Day from ' ...
or flared in a
lens A lens is a transmissive optical device which 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 ...
system, often in response to a bright light, producing a sometimes undesirable artifact in the image. This happens through light scattered by the imaging mechanism itself, for example through internal
reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...
and
forward scatter In physics, telecommunications, and astronomy, forward scatter is the deflection—by diffraction, nonhomogeneous refraction, or nonspecular reflection by particulate matter of dimensions that are large with respect to the wavelength in question ...
from material imperfections in the lens. Lenses with large numbers of elements such as
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tend to have more lens flare, as they contain a relatively large number of interfaces at which internal scattering may occur. These mechanisms differ from the focused image generation mechanism, which depends on rays from the refraction of light from the subject itself. There are two types of flare: visible artifacts and
glare Glare (derived from GLAss REinforced laminate ) is a fiber metal laminate (FML) composed of several very thin layers of metal (usually aluminum) interspersed with layers of S-2 glass-fiber ''pre-preg'', bonded together with a matrix such as epo ...
across the image. The glare makes the image look "washed out" by reducing contrast and color saturation (adding light to dark image regions, and adding white to saturated regions, reducing their saturation). Visible artifacts, usually in the shape of the
aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...
made by the
iris diaphragm In optics, a diaphragm is a thin opaque structure with an opening (aperture) at its center. The role of the diaphragm is to ''stop'' the passage of light, except for the light passing through the ''aperture''. Thus it is also called a stop (an ...
, are formed when light follows a pathway through the lens that contains one or more reflections from the lens surfaces. Flare is particularly caused by very bright light sources. Most commonly, this occurs when aiming toward the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
(when the Sun is in frame or the lens is pointed sunward), and is reduced by using a lens hood or other shade. For good-quality optical systems, and for most images (which do not have a bright light shining into the lens), flare is a secondary effect that is widely distributed across the image and thus not visible, although it does reduce contrast.


Manifestation

The spatial distribution of the lens flare typically manifests as several starbursts, rings, or circles in a row across the image or view. Lens flare patterns typically spread widely across the scene and change location with the camera's movement relative to light sources, tracking with the light position and fading as the camera points away from the bright light until it causes no flare at all. The specific spatial distribution of the flare depends on the shape of the
aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...
of the image formation elements. For example, if the lens has a 6-bladed aperture, the flare may have a hexagonal pattern. Such internal scattering is also present in the human eye, and manifests in an unwanted veiling
glare Glare (derived from GLAss REinforced laminate ) is a fiber metal laminate (FML) composed of several very thin layers of metal (usually aluminum) interspersed with layers of S-2 glass-fiber ''pre-preg'', bonded together with a matrix such as epo ...
most obvious when viewing very bright lights or highly reflective surfaces. In some situations,
eyelash An eyelash (also called lash) (Latin: ''Cilia'') is one of the hairs that grows at the edge of the eyelids. It grows in one layer on the edge of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and p ...
es can also create flare-like irregularities, although these are technically diffraction artifacts. When a bright light source is shining on the lens but not in its field of view, lens flare appears as a haze that washes out the image and reduces contrast. This can be avoided by shading the lens using a lens hood. In a studio, a gobo or set of
barn doors Stage lighting accessories are components manufactured for conventional (non-automated) stage lighting instruments. Most conventional fixtures are designed to accept a number of different accessories designed to assist in the modification of the out ...
can be attached to the lighting to keep it from shining on the camera. Filters can be attached to the camera lens which will also minimise lens flare, which is especially useful for outdoor photographers. When using an anamorphic lens, as is common in analog cinematography, lens flare can manifest itself as horizontal lines. This is most commonly seen in car headlights in a dark scene, and may be desired as part of the "film look".


Deliberate use

A lens flare is often deliberately used to invoke a sense of drama. A lens flare is also useful when added to an artificial or modified image composition because it adds a sense of realism, implying that the image is an un-edited original photograph of a "real life" scene. For both of these reasons (implying realism and/or drama) artificial lens flare is a common effect in various graphics editing programs, although its use can be a point of contention among professional
graphic design Graphic design is a profession, academic discipline and applied art whose activity consists in projecting visual communications intended to transmit specific messages to social groups, with specific objectives. Graphic design is an interdiscip ...
ers. Lens flare was one of the first special effects developed for
computer graphics Computer graphics deals with generating images with the aid of computers. Today, computer graphics is a core technology in digital photography, film, video games, cell phone and computer displays, and many specialized applications. A great de ...
because it can be imitated using relatively simple means. Basic flare-like effects, for instance in
computer and video games ''Computer and Video Games'' (also known as ''CVG'', ''Computer & Video Games'', ''C&VG'', ''Computer + Video Games'', or ''C+VG'') was a UK-based video game magazine, published in its original form between 1981 and 2004. Its offshoot website w ...
, can be obtained using static or animated starburst, ring, and disc textures that are moved according to the position of the light source. More sophisticated rendering techniques have been developed based on ray tracing or photon mapping. Lens flare was typically avoided by
Hollywood Hollywood usually refers to: * Hollywood, Los Angeles, a neighborhood in California * Hollywood, a metonym for the cinema of the United States Hollywood may also refer to: Places United States * Hollywood District (disambiguation) * Hollywoo ...
cinematographers, but when filming ''
Easy Rider ''Easy Rider'' is a 1969 American independent drug culture road drama film written by Peter Fonda, Dennis Hopper, and Terry Southern, produced by Fonda, and directed by Hopper. Fonda and Hopper play two bikers who travel through the American So ...
'' (1969), Harrison Arnold was forced to modify a camera car for his
Arriflex The Arri Group () is a German manufacturer of motion picture film equipment. Based in Munich, the company was founded in 1917. It produces professional motion picture cameras, lenses, lighting and post-production equipment. Hermann Simon menti ...
, which resulted in numerous lens flares as he shot motorcycle footage against landscapes of the
Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, N ...
. Director J. J. Abrams added numerous lens flares to his films ''
Star Trek ''Star Trek'' is an American science fiction media franchise created by Gene Roddenberry, which began with the eponymous 1960s television series and quickly became a worldwide pop-culture phenomenon. The franchise has expanded into vari ...
'' (2009) and '' Super 8'' (2011) by aiming powerful off-camera light sources at the lens. He explained in an interview about ''Star Trek'': "I wanted a visual system that felt unique. I know there are certain shots where even I watch and think, 'Oh that's ridiculous, that was too many.' But I love the idea that the future was so bright it couldn't be contained in the frame." Many complained of the frequent use; Abrams admitted it was "overdone, in some places." David Boyd, the director of photography of the sci-fi ''
Firefly The Lampyridae are a family of elateroid beetles with more than 2,000 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production ...
'' series, desired this style so much (harkening back to 1970s television), that he sent back cutting-edge lenses that reduced lens flare in exchange for cheaper ones.Whedon, ''Firefly: the complete series: "Serenity" commentary'' The first deliberate lens flare was made by cinematographer Hiroshi Segawa in the movie '' Woman in the Dunes'' in 1964. Earlier in the movies, lens flare was considered as defect and was strongly avoided. Director
Michael Bay Michael Benjamin Bay (born February 17, 1965) is an American film director and producer. He is best known for making big-budget, high-concept action films characterized by fast cutting, stylistic cinematography and visuals, and extensive use ...
, well known for heavy use of CGI in his films, digitally adds lens flares to most light sources in his films.


Other forms of photographic flare


Filter flare

The use of
photographic filter In photography and cinematography, a filter is a camera accessory consisting of an optical filter that can be inserted into the optical path. The filter can be of a square or oblong shape and mounted in a holder accessory, or, more commonly, a ...
s can cause flare, particularly ghosts of bright lights (under
central inversion In geometry, a point reflection (point inversion, central inversion, or inversion through a point) is a type of isometry of Euclidean space. An object that is invariant under a point reflection is said to possess point symmetry; if it is inv ...
). This can be eliminated by not using a filter, and reduced by using higher-quality filters or narrower aperture.


Diffraction artifact in digital cameras

One form of flare is specific to
digital cameras A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devices ...
. With the sun shining on an unprotected lens, a group of small rainbows appears. This artifact is formed by internal diffraction on the
image sensor An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of c ...
, which acts like a
diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structur ...
. Unlike true lens flare, this artifact is not visible in the eyepiece of a digital
SLR camera A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system (hence "reflex" from the mirror's reflection) that permits the photographer to view through the lens and see exactly what will be captured. With twin l ...
, making it more difficult to avoid.


Gallery

File:Lens Flare.jpg, Photograph of an
Apollo Lunar Module The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed ...
containing lens flare. Besides the obvious flare around the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, the light artifacts at the bottom right are also caused by flare. File:Artificial lens flare.png, Sample of artificial lens flare, as might be used in an animated movie or video game. File:High-quality lens flare rendering.png, High-end lens flare rendering using a recent technique File:Edinburgh-Princesstreet2.jpg, Lens flare is extremely difficult to control when a bright light source like the Sun is just outside the frame. File:Firework with lens flare.jpg, When the subject of a photo is the light source itself, lens flare can be a desirable and dramatic effect. File:Solar eclipse Austria 2011 Jan 04.JPG, Lens flare used to capture details of too bright motive (partial
solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six mon ...
). File:20100525 Imbros Marmaros Turkey example of Lens Flare.jpg, Lens flare - the Sun is outside the frame. File:'Perception of Christ Ascending to Heaven' Dome of the Rotunda of the church of the Holy Sepulchre Jerusalem Victor Grigas 2011 -1-19.jpg,
Dome A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...
of the Rotunda of the
Church of the Holy Sepulchre The Church of the Holy Sepulchre, hy, Սուրբ Հարության տաճար, la, Ecclesia Sancti Sepulchri, am, የቅዱስ መቃብር ቤተክርስቲያን, he, כנסיית הקבר, ar, كنيسة القيامة is a church i ...
,
Jerusalem Jerusalem (; he, יְרוּשָׁלַיִם ; ar, القُدس ) (combining the Biblical and common usage Arabic names); grc, Ἱερουσαλήμ/Ἰεροσόλυμα, Hierousalḗm/Hierosóluma; hy, Երուսաղեմ, Erusałēm. i ...
File:Mograph lensflare.png, Lens flare commonly associated with the use of anamorphic lenses which are often used in the production of films. File:Kensington Palace Gardens - London - UK.jpg, Lens flare example in picture of
Kensington Gardens Kensington Gardens, once the private gardens of Kensington Palace, are among the Royal Parks of London. The gardens are shared by the City of Westminster and the Royal Borough of Kensington and Chelsea and sit immediately to the west of Hyd ...
-
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
, UK File:Man playing guitar in a portrait with lens flare.jpg, alt=Lens flare example, Lens flare example in picture in a portrait. 50 mm at f1.4 File:Antony Leung - Oresteia - Stairwell Theater, 2019.jpg, Lens flare over Anthony Leung using theatre lighting during Stairwell Theater's
Oresteia The ''Oresteia'' ( grc, Ὀρέστεια) is a trilogy of Greek tragedies written by Aeschylus in the 5th century BCE, concerning the murder of Agamemnon by Clytemnestra, the murder of Clytemnestra by Orestes, the trial of Orestes, the end o ...
- Brooklyn, NY, 2019 File:MarsPerseveranceRover-Rainbow-20210404.png, Many mistook an April 4, 2021 lens flare on Mars, which appears in a ''
Perseverance Perseverance may refer to: Behaviour * Psychological resilience * Perseverance of the saints, a Protestant Christian teaching * Assurance (theology) Geography * Perseverance, Queensland, a locality in Australia * Perseverance Island, Seychelles ...
'' rover photograph, for a rainbow, until NASA clarified the issue. File:Lens flare Bow River trail Calgary, Alberta.jpg, Lens flare in shadow of poplar tree File:LensFlare.jpg, Extreme lens flare caused by intense sunlight.


See also

*
Anti-reflective coating An antireflective, antiglare or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses, other optical elements, and photovoltaic cells to reduce reflection. In typical imaging systems, this improves the ef ...
, used to reduce lens flare and produces the red and green colors common in lens flare. *
Bokeh In photography, bokeh ( or ; ) is the aesthetic quality of the blur produced in out-of-focus parts of an image. Bokeh has also been defined as "the way the lens renders out-of-focus points of light". Differences in lens aberrations and ...
, a source of circles around out-of-focus bright points, also due in part to the internals of the lens. * Diffraction spike, a type of lens flare seen in some
telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...
s


References

{{DEFAULTSORT:Lens Flare Science of photography Lenses Optical phenomena