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47-399: The Smooth Trans Focus ( STF ) technology in photographic lenses uses an apodization filter to realize notably smooth bokeh with rounded out-of-focus highlights in both the foreground and background. This is accomplished by utilizing a concave neutral-gray tinted lens element next to the aperture blades as apodization filter, a technology originally invented (and patented) by Minolta in

94-586: A camera car for his Arriflex as he shot motorcycle footage against landscapes of the Southwestern United States . David Boyd , the director of photography of the sci-fi Firefly series, desired this style's evocation of 1970s television so much that he sent back cutting-edge lenses that reduced lens flare in exchange for cheaper ones. The use of photographic filters can cause flare, particularly ghosts of bright lights (under central inversion ). This can be eliminated by not using

141-475: A UV coating to keep out the ultraviolet light that could taint color. Most modern optical cements for bonding glass elements also block UV light, negating the need for a UV filter. However, this leaves an avenue for lens fungus to attack if lenses are not cared for appropriately. UV photographers must go to great lengths to find lenses with no cement or coatings. A lens will most often have an aperture adjustment mechanism, usually an iris diaphragm , to regulate

188-414: 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 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

235-406: A doublet (two elements) will often suffice. Some older cameras were fitted with convertible lenses (German: Satzobjektiv ) of normal focal length. The front element could be unscrewed, leaving a lens of twice the focal length, and half the angle of view and half the aperture. The simpler half-lens was of adequate quality for the narrow angle of view and small relative aperture. This would require

282-599: A floating system; and Hasselblad and Mamiya call it FLE (floating lens element). Glass is the most common material used to construct lens elements, due to its good optical properties and resistance to scratching. Other materials are also used, such as quartz glass , fluorite , plastics like acrylic (Plexiglass), and even germanium and meteoritic glass . Plastics allow the manufacturing of strongly aspherical lens elements which are difficult or impossible to manufacture in glass, and which simplify or improve lens manufacturing and performance. Plastics are not used for

329-414: A lens used for a still camera , a video camera , a telescope , a microscope , or other apparatus, but the details of design and construction are different. A lens might be permanently fixed to a camera, or it might be interchangeable with lenses of different focal lengths , apertures , and other properties. While in principle a simple convex lens will suffice, in practice a compound lens made up of

376-408: A number of optical lens elements is required to correct (as much as possible) the many optical aberrations that arise. Some aberrations will be present in any lens system. It is the job of the lens designer to balance these and produce a design that is suitable for photographic use and possibly mass production. Typical rectilinear lenses can be thought of as "improved" pinhole "lenses" . As shown,

423-400: A pinhole "lens" is simply a small aperture that blocks most rays of light, ideally selecting one ray to the object for each point on the image sensor. Pinhole lenses have a few severe limitations: Practical lenses can be thought of as an answer to the question: "how can a pinhole lens be modified to admit more light and give a smaller spot size?". A first step is to put a simple convex lens at

470-595: 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 designers . Lens flare was one of the first special effects developed for computer graphics because it can be imitated using relatively simple means. Basic flare-like effects, for instance in video games , can be obtained by drawing starburst, ring, and disc textures over

517-436: A simple pinhole lens, but rather than being illuminated by single rays of light, each image point is illuminated by a focused "pencil" of light rays . From the front of the camera, the small hole (the aperture), would be seen. The virtual image of the aperture as seen from the world is known as the lens's entrance pupil ; ideally, all rays of light leaving a point on the object that enter the entrance pupil will be focused to

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564-412: A wider field of view than longer focal length lenses. A wider aperture, identified by a smaller f-number, allows using a faster shutter speed for the same exposure. The camera equation , or G#, is the ratio of the radiance reaching the camera sensor to the irradiance on the focal plane of the camera lens. The maximum usable aperture of a lens is specified as the focal ratio or f-number , defined as

611-630: Is believed to be the Carl Zeiss Planar 50mm f/0.7 , which was designed and made specifically for the NASA Apollo lunar program to capture the far side of the Moon in 1966. Three of these lenses were purchased by filmmaker Stanley Kubrick in order to film scenes in his 1975 film Barry Lyndon , using candlelight as the sole light source. The complexity of a lens — the number of elements and their degree of asphericity — depends upon

658-454: 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". 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

705-439: Is generally used to image close-up very small subjects. A macro lens may be of any focal length, the actual focus length being determined by its practical use, considering magnification, the required ratio, access to the subject, and illumination considerations. It can be a special lens corrected optically for close up work or it can be any lens modified (with adapters or spacers, which are also known as "extension tubes".) to bring

752-566: Is not true that all lenses with plastic elements are of low photographic quality. The 1951 USAF resolution test chart is one way to measure the resolving power of a lens. The quality of the material, coatings, and build affect the resolution. Lens resolution is ultimately limited by diffraction , and very few photographic lenses approach this resolution. Ones that do are called "diffraction limited" and are usually extremely expensive. Today, most lenses are multi-coated in order to minimize lens flare and other unwanted effects. Some lenses have

799-588: Is particularly caused by very bright light sources. Most commonly, this occurs when aiming toward the Sun (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. The spatial distribution of

846-405: Is the different distances from which a subject can be framed, resulting in a different perspective . Photographs can be taken of a person stretching out a hand with a wideangle, a normal lens, and a telephoto, which contain exactly the same image size by changing the distance from the subject. But the perspective will be different. With the wideangle, the hands will be exaggeratedly large relative to

893-470: The Box Brownie 's meniscus lens, to over 20 in the more complex zooms. These elements may themselves comprise a group of lenses cemented together. The front element is critical to the performance of the whole assembly. In all modern lenses the surface is coated to reduce abrasion, flare , and surface reflectance , and to adjust color balance. To minimize aberration, the curvature is usually set so that

940-555: The Pentax K mount are found across multiple brands, but this is not common today. A few mount designs, such as the Olympus/Kodak Four Thirds System mount for DSLRs, have also been licensed to other makers. Most large-format cameras take interchangeable lenses as well, which are usually mounted in a lensboard or on the front standard. The most common interchangeable lens mounts on the market today include

987-513: The angle of incidence and the angle of refraction are equal. In a prime lens this is easy, but in a zoom there is always a compromise. The lens usually is focused by adjusting the distance from the lens assembly to the image plane, or by moving elements of the lens assembly. To improve performance, some lenses have a cam system that adjusts the distance between the groups as the lens is focused. Manufacturers call this different things: Nikon calls it CRC (close range correction); Canon calls it

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1034-515: The bellows had to be extended to twice the normal length. Good-quality lenses with maximum aperture no greater than f/2.8 and fixed, normal, focal length need at least three (triplet) or four elements (the trade name " Tessar " derives from the Greek tessera , meaning "four"). The widest-range zooms often have fifteen or more. The reflection of light at each of the many interfaces between different optical media (air, glass, plastic) seriously degraded

1081-679: The contrast and color saturation of early lenses, particularly zoom lenses, especially where the lens was directly illuminated by a light source. The introduction many years ago of optical coatings, and advances in coating technology over the years, have resulted in major improvements, and modern high-quality zoom lenses give images of quite acceptable contrast, although zoom lenses with many elements will transmit less light than lenses made with fewer elements (all other factors such as aperture, focal length, and coatings being equal). Many single-lens reflex cameras and some rangefinder cameras have detachable lenses. A few other types do as well, notably

1128-400: The 1980s, and first implemented in a commercially available lens in 1999. In contrast to soft focus lenses , STF lenses render a perfectly sharp image in the focus plane. Lenses featuring Smooth Trans Focus technology: This photography-related article is a stub . You can help Misplaced Pages by expanding it . Photographic lens There is no major difference in principle between

1175-759: The Canon EF , EF-S and EF-M autofocus lens mounts. Others include the Nikon F manual and autofocus mounts, the Olympus / Kodak Four Thirds and Olympus/Panasonic Micro Four Thirds digital-only mounts, the Pentax K mount and autofocus variants, the Sony Alpha mount (derived from the Minolta mount) and the Sony E digital-only mount. A macro lens used in macro or "close-up" photography (not to be confused with

1222-490: The Mamiya TLR cameras and SLR, medium format cameras ( RZ67 , RB67 , 645-1000s)other companies that produce medium format equipment such as Bronica, Hasselblad and Fuji have similar camera styles that allow interchangeability in the lenses as well, and mirrorless interchangeable-lens cameras . The lenses attach to the camera using a lens mount , which contains mechanical linkages and often also electrical contacts between

1269-425: The amount of light that passes. In early camera models a rotating plate or slider with different sized holes was used. These Waterhouse stops may still be found on modern, specialized lenses. A shutter , to regulate the time during which light may pass, may be incorporated within the lens assembly (for better quality imagery), within the camera, or even, rarely, in front of the lens. Some cameras with leaf shutters in

1316-415: The angle of view, the maximum aperture, and intended price point, among other variables. An extreme wideangle lens of large aperture must be of very complex construction to correct for optical aberrations, which are worse at the edge of the field and when the edge of a large lens is used for image-forming. A long-focus lens of small aperture can be of very simple construction to attain comparable image quality:

1363-465: The aperture open until the instant of exposure to allow SLR cameras to focus with a brighter image with shallower depth of field, theoretically allowing better focus accuracy. Focal lengths are usually specified in millimetres (mm), but older lenses might be marked in centimetres (cm) or inches. For a given film or sensor size, specified by the length of the diagonal, a lens may be classified as a: A side effect of using lenses of different focal lengths

1410-436: The aperture, but in general these three will be in different places. Practical photographic lenses include more lens elements. The additional elements allow lens designers to reduce various aberrations, but the principle of operation remains the same: pencils of rays are collected at the entrance pupil and focused down from the exit pupil onto the image plane. A camera lens may be made from a number of elements: from one, as in

1457-597: The barrel or pressing a button which activates an electric motor . Commonly, the lens may zoom from moderate wide-angle, through normal, to moderate telephoto; or from normal to extreme telephoto. The zoom range is limited by manufacturing constraints; the ideal of a lens of large maximum aperture which will zoom from extreme wideangle to extreme telephoto is not attainable. Zoom lenses are widely used for small-format cameras of all types: still and cine cameras with fixed or interchangeable lenses. Bulk and price limit their use for larger film sizes. Motorized zoom lenses may also have

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1504-453: The compositional term close up ) is any lens that produces an image on the focal plane (i.e., film or a digital sensor) that is one quarter of life size (1:4) to the same size (1:1) as the subject being imaged. There is no official standard to define a macro lens, usually a prime lens , but a 1:1 ratio is, typically, considered "true" macro. Magnification from life size to larger is called "Micro" photography (2:1, 3:1 etc.). This configuration

1551-489: The flare depends on the shape of the aperture 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 most obvious when viewing very bright lights or highly reflective surfaces. In some situations, eyelashes can also create flare-like irregularities, although these are technically diffraction artifacts. When

1598-400: The focal plane "forward" for very close photography. Depending on the camera to subject distance and aperture, the depth-of-field can be very narrow, limiting the linear depth of the area that will be in focus. Lenses are usually stopped down to give a greater depth-of-field. Some lenses, called zoom lenses , have a focal length that varies as internal elements are moved, typically by rotating

1645-467: The focus, iris, and other functions motorized. Some notable photographic optical lens designs are: Lens flare A lens flare happens when light is scattered , or flared , in a lens 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 and forward scatter from material imperfections in

1692-479: The head. As the focal length increases, the emphasis on the outstretched hand decreases. However, if pictures are taken from the same distance, and enlarged and cropped to contain the same view, the pictures will have identical perspective. A moderate long-focus (telephoto) lens is often recommended for portraiture because the perspective corresponding to the longer shooting distance is considered to look more flattering. The widest aperture lens in history of photography

1739-421: The image and moving them as the location of the light source changes. More sophisticated rendering techniques have been developed based on ray tracing or photon mapping . Lens flare was typically avoided by Hollywood cinematographers, but the director J. J. Abrams deliberately added numerous lens flares to his films Star Trek (2009) and Super 8 (2011) by aiming powerful off-camera light sources at

1786-421: 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 made by the iris diaphragm , are formed when light follows a pathway through the lens that contains one or more reflections from the lens surfaces. Flare

1833-461: The lens and camera body. The lens mount design is an important issue for compatibility between cameras and lenses. There is no universal standard for lens mounts, and each major camera maker typically uses its own proprietary design, incompatible with other makers. A few older manual focus lens mount designs, such as the Leica M39 lens mount for rangefinders, M42 lens mount for early SLRs, and

1880-407: 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

1927-421: The lens omit the aperture, and the shutter does double duty. The two fundamental parameters of an optical lens are the focal length and the maximum aperture . The lens' focal length determines the magnification of the image projected onto the image plane, and the aperture the light intensity of that image. For a given photographic system the focal length determines the angle of view , short focal lengths giving

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1974-459: The lens's focal length divided by the effective aperture (or entrance pupil ), a dimensionless number. The lower the f-number, the higher light intensity at the focal plane. Larger apertures (smaller f-numbers) provide a much shallower depth of field than smaller apertures, other conditions being equal. Practical lens assemblies may also contain mechanisms to deal with measuring light, secondary apertures for flare reduction, and mechanisms to hold

2021-546: 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 conceded it was "overdone, in some places." In contrast, the low-budget independent film Easy Rider (1969) contains numerous incidental lens flares that resulted from Harrison Arnold 's need to modify

2068-405: The lens. Lenses with large numbers of elements such as zooms 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 across

2115-424: The outermost elements of all but the cheapest lenses as they scratch easily. Molded plastic lenses have been used for the cheapest disposable cameras for many years, and have acquired a bad reputation: manufacturers of quality optics tend to use euphemisms such as "optical resin". However many modern, high performance (and high priced) lenses from popular manufacturers include molded or hybrid aspherical elements, so it

2162-411: The pinhole with a focal length equal to the distance to the film plane (assuming the camera will take pictures of distant objects ). This allows the pinhole to be opened up significantly (fourth image) because a thin convex lens bends light rays in proportion to their distance to the axis of the lens, with rays striking the center of the lens passing straight through. The geometry is almost the same as with

2209-400: The same point on the image sensor/film (provided the object point is in the field of view). If one were inside the camera, one would see the lens acting as a projector . The virtual image of the aperture from inside the camera is the lens's exit pupil . In this simple case, the aperture, entrance pupil, and exit pupil are all in the same place because the only optical element is in the plane of

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