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''NEWS COLLECTION AND REPORTING''

REPORTER/CORRESPONDENT

A reporter is a type of journalist who researches and presents information in certain types of mass media.

Reporting is usually distinguished from similar work, such as writing in general, by news judgment (determining newsworthiness) and journalism values (such as fairness).

Reporters get their information in a variety of ways, including tips, press releases, and witnessing an event. They perform research through interviews, public records and other sources. The information-gathering part of the job is sometimes called "reporting" as distinct from the production part of the job, such as writing articles. They split their time between working in a newsroom and going out to witness events or interview people.

Most reporters are assigned an area to focus on, called a "beat". They are encouraged to "cultivate sources" so they won't miss news.

Reporters usually have a college degree. The degree is often in journalism, but that is not required. When hiring reporters, editors give much weight to the reporter's previous work, (such as newspaper "clips") even when written for a student newspaper or as part of an internship.

One common misconception is that newspaper reporters write the headlines for their articles, but those are written by copy editors.

ASSIGNMENT EDITOR

In journalism, an assignment editor is an editor – either at a newspaper, or radio or television station – who selects, develops and plans reporting assignments, either news events or feature stories, to be covered by reporters.

An assignment editor often fields calls from the public, who give news tips, or information about a possible story or event to be covered. Sometimes, these calls may:

Alert editors about a disaster – perhaps something as minor as a car accident or as major as a large industrial fire with mass casualties. Be someone wishing to make a complaint about corporate or governmental practices, or have information or an opinion about a major decision that a local or state government is making. Be something as minor as a child building the world's largest sand castle or a budding entrepreneuer wanting to promote his/her product. Other times, the news tip may come in the form of a news release, which may either promote an event, meeting, etc.; or alert editors and reporters about an upcoming news conference. Sometimes, assignment editors must sift through hundreds of news releases each day.

Whatever the case, it is the assignment editor's job to determine what news tips and news releases are the most newsworthy, and then decide which reporter to assign a story to. Those asisgnments are often determined based on the reporter's experience, skills and his/her beat (e.g., police, courts, schools, city hall, county, etc.).

If a major story develops – such as a disaster or economic development – an assignment editor may enlist several reporters (in addition to whomever usually covers that beat) to cover various angles of a story. For instance, if the story is about a plant closing, one reporter may be asked to do the main story about the closing, while other reporters may be asked to do stories on such things as employee reaction, reaction from business and community leaders, a history of the plant (and other plant closings, if appropriate), etc.

Required background An assignment editor often has at least one year of experience working for a particular news organization, and has good knowledge of the community in which he/she works and lives. Sometimes, it may be a journalist's first job as an editor, with other editorial sections – such as copy, section, managing and chief editors – higher in seniority.

At many smaller daily and weekly newspapers, the role of assignment editor is often combined with an editor's other duties (e.g., an assistant editor who also lays out the pages also may be asked to assign stories to reporters).

NEWS RELEASE

A news release, press release or press statement is a written or recorded communication directed at members of the news media for the purpose of announcing something claimed as having news value. Typically, it is mailed or faxed to assignment editors at newspapers, magazines, radio stations, television stations, and/or television networks. Commercial newswire services are also used to distribute news releases. Sometimes news releases are sent for the purpose of announcing news conferences.

A news release is different from a news article. A news article is a compilation of facts developed by journalists published in the news media, whereas a news release is designed to be sent to journalists in order to encourage them to develop articles on the subject. A news release is generally biased towards the objectives of the author.

The use of news releases is common in the field of public relations, the aim of which is to attract favorable media attention to the PR firm's client, and publicity, the aim of which is to attract favorable media attention for products marketed by the client.

PRESS CONFERENCE

A news conference or press conference is a media event in which newsmakers (or people claiming to be newsmakers) invite multiple journalists to hear them speak and,most often, ask questions.

There are two major reasons for holding a news conference. One is so that a newsmaker who gets many questions from reporters can answer them all at once rather than answering dozens of phone calls. Another is so someone can try to attract news coverage for something that was not of interest to journalists before.

In a news conference, one or more speakers may make a statement, which may be followed by questions from reporters. Sometimes only questioning occurs; sometimes there is a statement with no questions permitted.

A media event at which no statements are made, and no questions allowed, is called a photo opportunity.

Television stations and networks especially value news conferences: because today's TV news programs air for hours at a time, or even continuously, assignment editors have a steady appetite for ever-larger quantities of footage.

News conferences are often held by politicians (such as the President of the United States); by sports teams; by celebrities or film studios; by commercial organizations to promote products; by attorneys to promote lawsuits; and by almost anyone who finds benefit in the free publicity afforded by media coverage. Some people, including many police chiefs, hold news conferences reluctantly in order to avoid dealing with reporters individually.

A news conference is often announced by sending an advisory or news release to assignment editors, preferably well in advance. Sometimes they are held spontaneously when several reporters gather around a newsmaker.

News conferences can be held just about anywhere, in settings as formal as the White House room set aside for the purpose to as informal as the street in front of a crime scene. Hotel conference rooms and courthouses are often used for news confernences.

STRINGER

In journalism, a stringer is a freelance journalist, who is paid for each piece of published or broadcast work, rather than receiving a regular salary. In American newspapers the word carries a connotation of no-nonsense professionalism as compared to "freelancer," a term more likely to be used by newcomers to the business. The etymology of the word is uncertain. Newspapers once paid stringers so much money per inch of printed text, and one theory says the length of this text was measured against a string, hence the term. However, this seems unlikely, since editors in the pre-computer era were rarely at loss for a ruler.

EDITORS

An editor is a person who prepares text—typically language, but also images and sounds—for publication by correcting, condensing, or otherwise modifying it. In career terms, the word has four major senses:

Print media There are various levels of editorial positions in publishing. Typically one finds junior editorial assistants reporting to senior level editorial managers and directors, who themselves report to senior executive editors responsible for project development to final releases. See related articles at Journalism Visual media Editors in the visual mediums, who may be described as film or video editors, perform a variety of tasks. Assistant editors and production assistants perform preliminary screening and logging of motion picture footage; senior editors are responsible for creative placement of scenes and shots, structural placement of major elements and organization of the entire presentation. Other editors are involved with assembly of the final product and preparation for distribution. See related articles at film editor, video editor Sound media Motion pictures have many sound editors, this team works with various aspects of the picture or program's sound designers. These editors construct tracks consisting of assembled pre-recorded dialogue, the audio mixing in of sound effects, foley and music to achieve the desired effect for the motion pictures and television programs. See related articles at sound recording, sound effects, DAW Computer editor is a program used to make changes to files of a particular type. There are computer editing systems for visual and sound mediums as well as still images. Other types of editors are more technical and edit computer code in various ways needed by programmers and technicians. See related articles at word processor, Avid, electronic journalism Onto these career categories are mapped the categories in which individual professionals specialize, including language, still images, cinema/video, sound, computer programming code, and music scores. These areas sometimes overlap in individual practitioners; for example, language editors may comment on or make alterations to graphics and photographs embedded in a job that mostly comprises language; sound editors may make alterations in the linguistic text of, for example, a sound interview, to improve the intended meaning or reduce the duration of an item.

INVESTIGATING JOURNALISM

Investigative journalism is a kind of journalism in which reporters deeply investigate a topic of interest, often related to crime, scandals, government corruption, white collar crime. Whereas a typical daily or weekly news reporter writes items concerning immediately available news, an investigative journalist might spend months to years on a particular report. The investigation will often require an extensive number of interviews and travel, other instances might call for the reporter to make use of such as -- surveillance techniques, tedious analysis of documents, investigations of the performance of any kind of equipment involved in an accident, patent medicine, scientific analysis, social and legal issues and the like. In short, investigative journalism requires a lot of scrutiny of details, fact finding and physical effort. An investigative journalist must have an analytical and incisive mind with strong self-motivation to carry on when all doors are closed, when facts are being covered up or falsified and so on.

Most investigative journalism is done by newspapers and wire services.

                                  ==    PHOTOGRAPHY ==

CAMERA

A camera is a device used to take pictures (usually photographs), either singly or in sequence, with or without sound recording, such as with video cameras. A camera that takes pictures singly is sometimes called a photo camera to distinguish it from a video camera. The name is derived from camera obscura, Latin for "dark chamber", an early mechanism for projecting images in which an entire room functioned much as the internal workings of a modern photographic camera, except there was no way at this time to record the image short of manually tracing it. Cameras may work with the visual spectrum or other portions of the electromagnetic spectrum.

DESCRIPTION

Every camera consists of some kind of enclosed chamber, with an opening or aperture at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. This diameter of the aperture is often controlled by an diaphragm mechanism, but some cameras have a fixed-size aperture.

While the size of the aperture and the brightness of the scene control the amount of light that enters the camera during photographing, the shutter controls the length of time that the light hits the recording surface. For example, in lower light situations, the shutter speed should be slower (longer time spent open) to allow the film to capture what little light is present.

There are various ways of focusing a camera accurately. The simplest cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens (usually around 3 metres (10 feet) to infinity) is in reasonable focus. This is usually the kind found on one-use cameras and other cheap cameras. The camera can also have a limited focusing range or scale-focus that is indicated on the camera body. The user will guess or calculate the

distance to the subject and adjust the focus accordingly. On some cameras this is indicated by symbols (head-and-shoulders; two people standing upright; one tree; mountains).

Rangefinder cameras focus by means of a coupled parallax unit on top of the camera. Single-lens reflex cameras allow the photographer to determine the focus and composition visually using the objective lens and a moving mirror to project the image onto a ground glass or plastic micro-prism screen. Twin-lens reflex cameras use an objective lens and a focusing lens unit (usually identical to the objective lens) in a parallel body for composition and focusing. View cameras use a ground glass screen which is removed and replaced by either a photographic plate or a reusable holder containing sheet film before exposure.

Traditional cameras capture light onto photographic film or photographic plate. Video and digital cameras use electronics, usually a charge coupled device (CCD) or sometimes a CMOS sensor to capture images which can be transferred or stored in tape or computer memory inside the camera for later playback or processing.

Cameras that capture many images in sequence are known as movie cameras or as ciné cameras in Europe; those designed for single images are still cameras. However these categories overlap, as still cameras are often used to capture moving images in special effects work and modern digital cameras are often able to trivially switch between still and motion recording modes. A video camera is a category of movie camera which stores images onto magnetic tape either using analogue or digital technology).

Stereo camera can take photographs that appear "three-dimensional" by taking two different photographs which are combined to create the illusion of depth in the composite image. Stereo cameras for making 3D prints or slides have two lenses side by side. Stereo cameras for making lenticular prints have 3, 4, 5, or even more lenses.

Some film cameras feature date imprinting devices that can print a date on the negative itself.

APERTURE

In optics, an aperture is something which restricts the diameter of the light path through one plane in an optical system. This may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or it may be a special element placed in the optical path deliberately to limit the light admitted by the system. The aperture stop or simply the stop is the limiting aperture of the system—the aperture which restricts the diameter of the cone or cylinder of light that can enter and pass through the system. The diameter of the aperture stop is sometimes simply referred to as the aperture of the system, especially when speaking of cameras and telescopes. Note that the aperture stop is not necessarily the smallest aperture in the system. Magnification and demagnification by lenses and other elements can cause a relatively large aperture to be the stop for the system.

The aperture stop is an extremely important element in most optical designs. Its most obvious function is to reduce the amount of light that can reach the image plane, to prevent saturation of a detector or overexposure of film. The aperture stop has far more important functions, however:

The size of the stop determines the depth of field of the system. Smaller stops produce a longer depth of field, allowing objects at a wide range of distances to all be in focus at the same time. The stop limits the effect of optical aberrations. If the stop is too large, the image will be distorted. More sophisticated optical system designs can mitigate the effect of aberrations, allowing a larger stop and therefore greater light collecting ability. The stop determines the system's field of view. The stop determines whether the image will be vignetted. Larger stops cause the intensity reaching the film or detector to fall off toward the edges of the picture. The pupil of the eye is its aperture stop. Refraction in the cornea causes the effective aperture (the entrance pupil) to differ slightly from the physical pupil diameter. The entrance pupil is typically about 4 mm in diameter, although it can range from 2 mm (f/8.3) in a brightly lit place to 8 mm (f/2.1) in the dark.

The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or digital sensor (CCD or CMOS). In combination with variation of shutter speed and film speed, the aperture size will regulate the film's degree of exposure to light. Typically, a fast shutter speed will require a larger aperture to ensure sufficient light exposure, and a slow shutter speed will require a smaller aperture to avoid excessive exposure.

A device called a diaphragm controls the aperture. The diaphragm can be considered to function much like the pupil of the eye—it controls the effective diameter of the lens opening. Reducing the aperture size increases the depth of field, which describes the extent to which subject matter lying closer than or farther from the actual plane of focus appears to be in focus. In general, the smaller the aperture (the larger the number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus.

Diagram of decreasing aperture f-stopsAperture is usually measured in f-numbers. A lens will have a set of "f-stops" that represent doublings in the amount of light let through the aperture. A lower f-stop number denotes a greater aperture opening which allows more light to reach the film. A typical standard lens will have an f-stop range from f/16 (small aperture) to f/2 (large aperture). Professional lenses can have f-stops as low as f/1.0 (very large aperture). These are known as "fast" lenses because they allow much more light to reach the film and therefore reduce the required exposure time. Large aperture prime lenses (lenses which have a fixed focal length) are favored especially by photojournalists who often work in dim light, have no opportunity to introduce supplementary lighting, and capture fast breaking events.

Zoom lenses typically go from f/2.8 to f/6.3. A very fast zoom lens will be constant f/2.8, which means the aperture will stay the same throughout the zoom range. A normal zoom will be a constant f/4, and a consumer zoom will typically have a variable diaphragm, normally being something along the lines of f/4.5 to f/5.6, or even f/4.5 to f/6.3 (rare). There are a few exceptions to this rule, as even high quality hyperzooms often have as slow of an aperture as f/5.6 throughout the whole zoom range. Such is the case with most lenses which have more than 4x zoom range, like a 100-400 mm f/5.6.

The reason for consumer zooms to have a variable aperture is that the f-number is proportional to the ratio of the focal length to the diameter of the diaphragm opening. This means that if you have a 75-300 mm lens, a physically bigger diaphragm opening will be needed at 300 mm than at 75 mm, to maintain the same f-number. More light is needed as the focal length increases, to compensate for the fact that light from a smaller field of view is being spread over the same area of film or detector.

[edit] Maximum and minimum apertures

f/32 - narrow aperture and low shutter speed

f/5 - wide aperture and high shutter speed The specifications for a given lens might include the minimum and maximum apertures. These refer to the maximum and minimum f-numbers the lens can be set at to achieve, respectively, the minimum and maximum input of light. For example, the Canon EF 70-200mm lens has a maximum aperture of f/2.8 and a minimum aperture of f/32. This may seem counterintuitive since the maximum aperture has a smaller number while the minimum aperture has a larger number, but makes sense since the smaller number corresponds to a physically larger aperture opening. This can be remembered by thinking of the f/numbers as fractions and recalling that 1/2.8 is greater than 1/32.

It should be noted that the maximum aperture tends to be of most interest (makes it easier to shoot under dim lighing conditions because the lens lets more light through to the film or CCD) and is usually included when describing a lens (e.g., 100-400mm f/5.6, 70-200mm f/2.8).

The minimum aperture is useful for time-lapse pictures shot on film (it places an upper limit on the exposure time for a given lighting condition) and maximum depth of field.

DEPTH OF FIELD

In optics, particularly film and photography, the depth of field (DOF) is the distance in front of and behind the subject which appears to be in focus. For any given lens setting, there is only one distance at which a subject is precisely in focus, but focus falls off gradually on either side of that distance, so there is a region in which the blurring is tolerable. This region is greater behind the point of focus than it is in front, as the angle of the light rays change more rapidly; they approach being parallel with increasing distance.

FOCUS

Several factors determine whether the objective error in focus becomes noticeable. Subject matter, movement, the distance of the subject from the camera, and the way in which the image is displayed all have an influence. However, the most important factor is the actual degree of error in relation to the area of film exposed.

Light from a point source at the correct distance will produce the image of a point on the film. A point farther away or nearer will produce the image of a disk whose border is known as "circle of confusion." The diameter of these circles increases with distance from the point of focus and so can be used as the measure of error or blurring of the image.

The area within the depth of field appears sharp while the areas in front and behind the depth of field appear blurry.For a 35 mm motion picture, the image area on the camera negative is roughly 0.87 by 0.63 in (22 by 16 mm). The limit of tolerable error is usually set at 0.002 in (0.05 mm) diameter. For 16 mm film, where the image area is smaller, the tolerance is stricter, .001 in (0.025 mm). Standard depth of field tables are constructed on this basis, although generally 35 mm productions set it at 0.001 in (0.025 mm). Note that the acceptable circle of confusion values for these formats are different because of the relative amount of magnification each format will need in order to be projected on a full-sized movie screen.

(A table for 35 mm still photography would be somewhat different since more of the film is used for each image and the amount of enlargement is usually much less.)

Another factor to be considered is that the film format's size will affect the relative depth of field. The larger the area of the film is, the longer a lens will need to be to capture the same framing as a smaller film format. In motion pictures, for example, a frame with a 12 degree horizontal field of view will require a 50 mm lens on 16 mm film, a 100 mm lens on 35 mm film, and a 250 mm lens on 65 mm film. Conversely, using the same focal length lens with each of these formats will yield a progressively wider image as the film format gets larger: a 50 mm lens has a horizontal field of view of 12 degrees on 16 mm film, 23.6 degrees on 35 mm film, and 55.6 degrees on 65 mm film. What this all means is that as the larger formats require longer lenses than the smaller ones, they will accordingly have a smaller depth of field. Therefore, compensations in exposure, framing, or subject distance need to be made in order to make one format look like it was filmed like another.

ANGLE OF VIEW

In photography, angle of view (also called Angle of Coverage or Field of View) is the amount of a given scene shown on film; that is, there is generally much more to a scene visible to humans than shows up in photos, and various lenses record different degrees of the total image. There are also different ways to measure the angle of view:

horizontally diagonally vertically Angle of view is affected by choice of lens:

wide-angle lenses get considerably wider angle of view than telephoto lenses with a fisheye lens recording up to 180° of a scene the longest lenses recording less than 2° (e.g., the Canon EF 1200mm lens has a horizontal viewing angle of 1°45′) Longer lenses tend to magnify the subject, 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. One result of using a wide angle lens in close proximity to the subject is an apparent perspective distortion: parallel lines may appear to converge and with a fisheye lens, straight edges will appear to bend.

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.

TELEPHOTO LENSES

In photography and cinematography, a telephoto lens is a lens whose focal length is significantly longer than the focal length of a normal lens. For a 35 mm camera with a 36 mm x 24 mm format (43.3 mm diagonal), the normal lens is 50 mm and a lens of focal length 70 mm or more is considered telephoto. On the 6 cm x 6 cm format (84.9 mm diagonal) (120 film) the normal lens is 80 mm, and focal lengths above 100 mm are considered telephoto.

Telephoto lenses are best known for making distant objects appear larger. This effect is similar to moving closer to the object, but is not the same, since a telephoto will produce a different perspective. Telephoto lenses also have less depth of field at a given aperture than shorter lenses.

Regarding optical design a telephoto lens must contain a telephoto group, which allows the lens to be physically shorter than its focal length. A lens with a conventional design and a focal length longer than a normal lens should properly be referred to as long focus. Still, common nomenclature simply refers to all long-focus lenses as telephoto.

Compare with the opposite effect used in retrofocus lenses (sometimes designed as inverted telephotos), which have greater clearance from the rear element to the film plane than their focal length would permit with a conventional optical design.

LENSES

A photographic lens (or more correctly, objective) is an optical lens used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.

While in principle a simple convex lens will suffice, in practice a compound lens made up of a number of optical lens elements is required to correct the many optical aberrations that arise.

There is no difference in principle between a lens used for a camera, a telescope, a microscope, or other apparatus, but the detailed design and construction are different.

A lens may be permanently fixed to a camera, or it may be interchangeable with lenses of different focal lengths and other properties.

A practical camera lens will often incorporate an aperture adjustment mechanism, often an iris diaphragm, to regulate the amount of light that may pass. A shutter, to regulate the time during which light may pass, may be incorporated within the lens assembly, or may be within the camera, or even, rarely, in front of the lens.

The lens may usually be focused by adjusting the distance from the lens assembly to the image-forming surface, or by moving elements within the lens assembly.

The lens elements are made of transparent materials. Glass is the most widely used material due to its good optical properties and resistance to scratching. Various plastics, such as acrylic (or PMMA), the material of Plexiglas, can also be used. Plastics allow the manufacture of strongly aspherical lens elements which are difficult or impossible to manufacture in glass, and which simplify or improve lens manufacture and performance. Plastics are not used for the outermost elements of all but the cheapest lenses as they scratch easily. Moulded 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".

The maximum usable aperture of a lens is usually specified, as the focal ratio or f-number, the focal length divided by the actual aperture in the same units. The lower the number, the more light is admitted through the lens. Practical lens assemblies may also contain mechanisms to do with measuring light, to hold the aperture open until the instant of exposure to allow SLR cameras to focus with a bright image, etc.

The two main optical parameters of a photographic lens are the focal length and the maximum aperture. The focal length determines the angle of view, the size of the image relative to that of the object, and the perspective; the maximum aperture limits the brightness of the image and the fastest shutter speed usable.

Focal lengths are usually specifed in millimeters (mm), but older lenses marked in centimeter (cm) and inches are still to be found. For a given film or sensor size, specifed by the length of the diagonal, a lens may be classified as

Normal lens: angle of view of the diagonal about 50°, the same as the human eye: a focal length approximately equal to the diagonal produces this angle. Wide-angle lens: focal length shorter than normal, and angle of view wider. Long-focus or telephoto lens: focal length longer than normal, and angle of view narrower. A distinction is sometimes made between a long-focus lens and a true telephoto lens: the telephoto lens is designed to be physically shorter than its focal length. The 35mm film format is so prevalent that a 90mm lens, for example, is always assumed to be a moderate telephoto; but for the 7x5cm format it is normal, while on the large 5x4 inch format it is a wide-angle.

The real difference between lenses of different focal length is not the image size, but the perspective. You can take photographs 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 your distance from the subject. But the perspective will be different. With the wideangle, the hand will be exaggeratedly large relative to the head; as the focal length increases, the emphasis on the outstretched hand decreases. However, if you take pictures from the same distance, and enlarge and crop them to contain the same view, the pictures will be truly identical. A moderate long-focus (telephoto) lens is often recommended for portraiture because the flatter perspective is considered to look more realistic.

Some lenses, called zoom lenses, have a focal length which varies as internal elements are moved, typically by rotating the barrel or pressing a button which activates an electric motor. 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.

The complexity of a lens—the number of elements and their degree of asphericity—depends upon the angle of view and the maximum aperture. 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; a doublet (with two elements) will often suffice. Some older cameras were fitted with "convertible" lenses of normal focal length; the front element could be unscrewed, leaving a lens of twice the focal length and 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. Obviously the bellows had to extend to twice the normal length.

Good-quality lenses with maximum aperture no greater than f/2.8 and fixed, normal, focal length need 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 the contrast and color saturation of early lenses, zoom lenses in particular, 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.

SHUTTER SPEED

In photography, shutter speed is the time for which the shutter is held open during the taking of a photograph to allow light to reach the film or imaging sensor(in a digital camera).

In combination with variation of the lens aperture, this regulates how exposed the film will be or how much light the imaging sensor in a digital camera will receive. For a given exposure, a fast shutter speed demands a larger aperture to avoid under-exposure, just as a slow shutter speed is offset by a very small aperture to avoid over-exposure. Long shutter speeds are often used in low light condition, such as at night.

Shutter speed is measured in seconds. A typical shutter speed for photographs taken in sunlight is 1/125th of a second. In addition to its effect on exposure, shutter speed changes the way movement appears in the picture. Very short shutter speeds are used to freeze fast-moving subjects, for example at sporting events. Very long shutter speeds are to intentionally blur a moving subject for artistic effect.

In early days of photography, available shutter speeds were somewhat ad hoc. Following the adoption of a standardized way of representing aperture so that each major aperture interval exactly doubled or halved the amount of light entering the camera (f/2.8, f/4, f/5.6, f/8, f/11, f/16 etc.), a standardized 2:1 scale was adopted for shutter speed so that opening one aperture stop and reducing the shutter speed by one step resulted in the identical exposure. The agreed standard for shutter speeds is:

1/8000 s 1/4000 s 1/2000 s 1/1000 s 1/500 s 1/250 s 1/125 s 1/60 s 1/30 s 1/15 s 1/8 s 1/4 s 1/2 s 1 s B (for bulb) — keep the shutter open as long as the release lever is engaged. T — keep the shutter open until the lever is pressed again. This scale can be extended at either end in specialist cameras.

The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of slowest possible shutter speed for a handheld camera. The rough guide used by most 35mm photographers is that the slowest possible shutter speed that can be used with care is the shutter speed numerically closest to the lens focal length. For example, for handheld use of a 35 mm camera with a 50 mm normal lens, the closest shutter speed is 1/60 s. For a free-standing, unsupported photographer it is usually necessary to use the next fastest shutter speed which would be 1/125 s in this case. With great care its possible to use 1/30s with the 50mm lens, or even slower speed especially with non-SLR cameras. Note that using this with "great care" would normally mean bracing the camera, arms, or body to minimise camera movement. If a shutter speed is too slow for hand holding, a camera support—usually a tripod—must be used.

Other 35 mm handheld examples are:

28 mm wide angle lens, 1/30 s may be used with care, and 1/60 s is advised. 105 mm medium telephoto lens, 1/125 s may be used with care, and 1/250 s is advised. 300 mm long telephoto lens, 1/250 s may be used with care, and 1/500 s is advised.

EXPOSURE

In photography, exposure is the total amount of light allowed to fall on the sensor (photographic film or CCD) during the process of taking a photograph. Exposure is measured in exposure value (ev), with higher values denoting more light.

The "correct" exposure for a photograph is determined by the sensitivity of the sensor used. For photographic film, sensitivity is referred to as film speed and is measured on a scale published by the International Organization for Standardization (ISO). Faster film requires less exposure and has a higher ISO rating. Exposure is controlled in a camera by shutter speed and lens aperture. Slower shutter speeds and greater lens apertures produce greater exposures. The electronincs in a digital camera may allow one to adjust the sensitivity of the CCD. ISO numbers are usually used to express this attribute.

An approximately correct exposure will be obtained on a sunny day using ISO 100 film, an aperture of f/16 and a shutter speed of 1/125th of a second. This is called the sunny f/16 rule.

An important principle of exposure is reciprocity. If one exposes the sensor for a longer period, a reciprocally smaller aperture is required to reduce the amount of light hitting the film to obtain the same exposure. For example, the photographer may prefer to make his sunny-16 shot at an aperture of f/5.6 (to obtain a shallow depth of field). As f/5.6 is 3 stops 'faster' than f/16, with each stop meaning double the amount of light, a new shutter speed of (1/125)/(2*2*2) = 1/1000 is needed. Once the photographer has determined the exposure, aperture stops can be traded for halvings or doublings of speed, within limits.

A demonstration of the effect of exposure in night photography. Longer shutter speeds mean increased exposure.

The true characteristic of most photographic emulsions is not actually linear, (see sensitometry) but it is close enough over the exposure range of about one second to 1/1000th of a second. Outside of this range, it becomes necessary to increase the exposure from the calculated value to account for this characteristic of the emulsion. This characteristic is known as reciprocity failure. The film manufacturer's data sheets should be consulted to arrive at the correction required as different emulsions have different characteristics.

The Zone System is another method of determining exposure.

Today, most cameras automatically determine the correct exposure at the time of taking a photograph by using a built-in light meter, or multiple point meters interepreted by a built-in computer, see metering mode.

FILM SPEED

Film speed is the measure of a photographic film stock's sensitivity to light. Stock with lower sensitivity requires a longer exposure and is thus called a slow film, while stock with higher sensitivity can shoot the same scene with a shorter exposure and is called a fast film.

The standard known as ISO 5800:1987 from the International Organization for Standardization (ISO) defines both a linear scale and a logarithmic scale for measuring film speed.

In the ISO linear scale, which corresponds to the older ASA scale, doubling the speed of a film(that is, halving the amount of light that is necessary to expose the film) implies doubling the numeric value that designates the film speed. In the ISO logarithmic scale, which corresponds to the older DIN scale, doubling the speed of a film

GOST (Russian ГОСТ) Pre-1987 Standard in the former Eastern Bloc. After 1987 GOST scale was changed to align with ISO scale. Only found on pre-1987 photographic equipment (Film, Cameras, Lightmeters) of Eastern Bloc manufacture.

The most common ISO film ratings are 25/15°, 50/18°, 100/21°, 200/24°, 400/27°, 800/30°, 1600/33°, and 3200/36°. Consumer films are generally rated between 100/21° and 800/30°, inclusive.

The following table shows the correspondence between these scales:

ISO linear scale (old ASA scale) ISO log scale (old DIN scale) GOST (Soviet pre-1987) Example of film stock with this nominal speed 6 9° 8 10° 10 11° 12 12° 11 16 13° 11 20 14° 16 25 15° 22 old Agfacolor, Kodachrome 25 32 16° 22 40 17° 32 Kodachrome 40 (movie) 50 18° 45 Fuji RVP (Velvia) 64 19° 45 Kodachrome 64 80 20° 65 Ilford Commercial Ortho 100 21° 90 Kodacolor Gold, Kodak T-Max (TMX) 125 22° 90 Ilford FP4 160 23° 130 Fuji NPS 200 24° 180 Fujicolor Superia 200 250 25° 180 320 26° 250 Kodak Tri-X Pan (TXP) 400 27° 350 Kodak T-Max (TMY) 500 28° 350 640 29° 560 800 30° 700 Fuji NPZ 1000 31° 700 Ilford Delta 3200 (see text below) 1250 32° 1600 33° Fujicolor 1600 2000 34° 2500 35° 3200 36° 4000 37° 5000 38° 6400 39°

A film speed is converted from the linear scale to the logarithmic scale by this formula (plus rounding to the nearest integer):

Conversion from the logarithmic scale to the linear scale is analogous, except that results must be rounded to the conventional values of the linear scale listed in the table above.

Film speed is found by referencing the Hurter & Driffield curve for the film. This is a plot of density vs. exposure (lux-s). There are typically five regions in the curve: the base + fog, the toe, the linear region, the shoulder, and the overexposed region. Following the curve to the point where it exceeds the base + fog by 10%, find the corresponding exposure. Dividing 0.1 into that yields the speed.

The speed is used in the Exposure Index equation to find the appropriate exposure. Four variables are available to the photographer to obtain the desired effect: light, film speed, f/#, and exposure time (shutter speed). The equation may be expressed as ratios, or, by taking the logarithm (base 2) of both sides, by addition. In this form, it was easier at the time it was proposed to put into a nomograph (slide rule) so non-scientists could obtain good results. As a result, every increment of 1 is a doubling of light intensity, known as a "stop". The f/# is the ratio between the lens focal length and aperture, which in turn is proportional to the lens area by the square root. Thus, a lens set to f/1.4 allows twice as much light to strike the focal plane as a lens set to f/2. Therefore, each increment of the square root of two (approximately 1.4) is also a stop, so lenses are typically marked in that progression: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc.

Speed is roughly related to granularity, the size of the grains of silver halide in the emulsion. Fine-grain stock, such as portrait film or those used for the intermediate stages of copying original camera negatives, is "slow", meaning that the amount of light used to expose it must be high or the shutter must be open longer. Fast films, used for shooting in poor light or for shooting fast motion, produce a grainy image. The image actually consists of a mosaic of developed and undeveloped areas of the emulsion, and each grain of silver halide develops in an all-or-nothing way. Thus, film is a threshold detector rather than a linear detector. If the subject has an edge between light and darkness and that edge falls on a grain, the result will be an area that is all light or all shadow. An accumulation of such areas breaks up the visible contours of the object, the effect known as graininess (or grain). Fast films are also relatively contrasty, for the same reason. That is, an area of the image will consist of bright areas and dark ones with few transitional areas of midtones.

Kodak used to use a Granularity Index (GI) to characterize film grain. Alternating images of the film under test and a standard grain were shown to test subjects who indicated when they perceived a match. The standard grain samples were the index. More recently, Kodak switched to a measurement of grain using an RMS measurement. Granularity varies with exposure - underexposed film looks grainier than overexposed film.

In the early 1980s, there were some radical improvements in film stock. It became possible to shoot color film in very low light and produce a fine-grained image with a good range of midtones. In advertising, music videos, and some drama, mismatches of grain, color cast, and so forth between shots are often deliberate and added in post-production.

Certain high-speed black-and-white films, such as Ilford Delta 3200 and Kodak T-Max P3200 (TMZ), are marketed with higher speeds on the box than their true ISO speed (determined using the ISO testing methodology). For example, the Ilford product is actually an ISO 1000 film, according to its data sheet. The manufacturers are careful not to refer to the 3200 speed as an ISO speed on the packaging. These films can be successfully exposed at EI 3200 (or any of several other speeds) through the use of push processing.

SLR CAMERAS

The single-lens reflex (SLR) is a type of camera that uses a movable mirror placed between the lens and the film to project the image seen through the lens to a matte f ocusing screen. Most SLRs use a pentaprism to observe the image via an eyepiece, but there are also other finder arrangements, such as the waist-level finder or porro prisms.

The shutter in almost all contemporary SLRs sits just in front of the focal plane. If it does not, some other mechanism is required to ensure that no light reaches the film between exposures. For example, the Hasselblad 500C camera uses an auxiliary shutter blind in addition to its in-lens leaf shutter.

Since the technology became widespread in the 1970s, SLRs have become the main type of camera used by dedicated amateur photographers and professionals.

ADVANTAGES OF SLR CAMERAS

Many of the advantages of SLR cameras derive from viewing the scene through the taking lens. There is no parallax error, and exact focus can be confirmed by eye—otherwise hard for macro photography and when using telephoto lenses. The true depth of field may be seen by stopping down to the taking aperture, possible on all but the cheapest cameras. Because of the SLR's versatility, most manufacturers have a vast range of lenses and accessories available. Only the Leica rangefinder cameras have a comparable system.

Compared to most fixed-lens compact cameras, the most commonly used and cheapest SLR lenses offer a wider aperture range and larger maximum aperture (typically f/1.4 to f/1.8 for a 50 mm lens). This allows photographs to be taken in lower light conditions without flash, and allows a narrower depth of field, which is useful for blurring the background behind the subject, which makes the subject stand out better. This is commonly used in portrait photography.

DISADVANTAGES OF SLR CAMERAS

The most obvious disadvantage of the SLR is its greater weight and size than rangefinders of a similar technology level. The pentaprism and mirror box make the camera body larger. However, rangefinders have not advanced significantly since the 1970s, while modern SLRs use advanced automation and electronics to be smaller and plastics to save weight.

The SLR's space-consuming mirror movement makes for difficulty in constructing wide angle lenses; rear lens elements cannot be close to the film plane. Retrofocus designs are required for wide-angle lenses; these are complex, large, and comparatively poorer in image quality.

The reflex mirror must retract before the shutter can open, which introduces some delay. Autofocus systems on modern SLRs introduce further delay, especially in lower light. The mirror's movement also causes vibration and noise, a problem when using longer lenses and longer exposures. Technology has reduced but not eliminated this problem, which again is worse in larger formats. To combat this, higher-end cameras offer the ability to lock up the mirror before the shot is taken. This eliminates the vibration but blacks out the viewfinder.

The SLR user cannot see anything outside the taking frame through the viewfinder, while with most rangefinder systems, this can be done. This helps in certain kinds of photography. Only higher-end SLRs show the full frame; typical coverage is 90%. Print labs generally crop an equivalent area, so it is less of a problem than it might otherwise be.

TLR CAMERAS

A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective (the lens that takes the picture), while the other is used for the waist-level viewfinder system. In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive TLRs are fixed-focus models.

Higher-end TLRs may have a pop-up magnifying glass to assist the user in focusing the camera. In addition, many have a "sports finder" consisting of a square hole punched in the back of the pop-up hood, and a knock-out in the front. Photographers can sight through these instead of using the matte screen. This is especially useful in tracking moving subjects such as animals, since the image on the matte screen is reversed left-to-right.

Rollei Rolleiflex model TLRs have an additional feature for the "sports finder" that allows precise focusing. When the hinged front hood knock-out is moved to the sports finder position a secondary mirror swings down over the view screen to reflect the image to a secondary magnifier on the back of the hood, just below the direct view cutout. This permits precise focusing while using the sports finder feature. The magnified central image is reveresed both top to bottom and left to right.

TLRs are different from single-lens reflex cameras (SLR) in several respects. First, unlike most SLRs, TLRs provide a continuous image on the finder screen. The view does not black out during exposure. Additionally, models with leaf shutters rather than focal-plane shutters can synchronize with flash at higher speeds than can SLRs. However, because the photographer views through one lens but takes the photograph through another, parallax error makes the photograph different from the view on the screen. This difference is negligible when the subject is far away, but is critical for nearby subjects. For accuracy in tabletop photography, in which the subject might be within a foot (30 cm) of the camera, devices are available that move the camera upwards so that the taking lens goes to the exact position that the viewing lens occupied.

A primary advantage of the TLR is its simplicity as compared to the more common single-lens reflex cameras. The SLR must employ some method of blocking light from reaching the film during focusing, either with a focal plane shutter (most common) or with the reflex mirror itself. Both methods add significant noise to the camera's operation. Most TLRs use a leaf shutter in the lens. The only mechanical noise during exposure is from the shutter leaves opening and closing.

The typical TLR is medium format, using 120 roll film with square 6 x 6 cm images. Presently, the Chinese Seagull and the German Rollei are in production, but in the past, many manufacturers made them. Models with the Mamiya, Minolta and Yashica brands are common on the used-camera market, and many other companies made TLRs that are now classics.

There were smaller TLR models, using 127 roll film with square 4 x 4 cm images, most famous the "Baby" Rolleiflex and the Yashica 44. The TLR style was also popular in the 1950s for inexpensive fixed-focus cameras such as the Kodak Duaflex and Argus 75.

WIDE ANGLE LENSES

In photography and cinematography, a wide-angle lens is a lens whose focal length is shorter than the focal length of a normal lens. For a 35 mm camera with a 36 mm by 24 mm format, the normal lens is 50 mm. A lens of focal length 35 mm or less is considered wide-angle.

In addition to giving a wider angle of view, the resulting image can also have perspective distortion.

Common wide-angle lenses for a 35 mm camera are 35, 28, 24, 20, 17 and 14 mm. These lenses will give a rectilinear projection.

Extreme wide-angle lenses normally do not give a geometric projection, and are called fisheye lenses. Common focal lengths for a 35 mm camera are 6 to 8 mm (will give a circular image), and 15 or 16 mm (will give a curvilinear, full-frame, image).

Projection of these lenses can be described by the shape of the projection area (for geometric projection). Normal (perfect) lenses use rectangles, (perfect) fish eyes use parts of spheres or cylinders.

There is no distortion when imaging and projection are done by lenses with the same projection theme.