Thursday, January 7, 2010

CLOSE UP SHOT


CLOSE UP SHOT
In film, television, still photography and the comic strip medium a close-up tightly frames a person or an object.
Close-ups are one of the standard shots used regularly with medium shots and long shots. Close-ups display the most detail,
but they do not include the broader scene. Moving in to a close-up or away from a close-up is a common type of zooming.
Close-ups are used in many ways, for many reasons. Close-ups are often used as cutaways from a more distant shot to show detail,
such as characters' emotions, or some intricate activity with their hands. Close cuts to characters' faces are used far more often
in television than in movies; they are especially common in soap operas. For a director to deliberately avoid close-ups may create
in the audience an emotional distance from the subject matter.
Close-ups are used for distinguishing main characters. Major characters are often given a close-up when they are introduced as a way
of indicating their importance. Leading characters will have multiple close-ups. There is a long-standing stereotype of insecure actors
desiring a close-up at every opportunity and counting the number of close-ups they received. An example of this stereotype occurs when
the character Norma Desmond in Sunset Boulevard, announces "All right, Mr. DeMille, I'm ready for my close-up" as she is taken into
police custody in the film's finale.
Close-up shot of a dog.Close-up shots do not show the subject in the broad context of its surroundings.
If overused, close-ups may leave viewers uncertain as to what they are seeing. Close-ups are rarely done with wide angle lenses,
because perspective causes objects in the center of the picture to be unnaturally enlarged. Certain times, different directors will
use wide angle lenses, because they can convey the message of confusion, and bring life to certain characters.

MEDIUM SHOT









MEDIUM SHOT
In film, a medium shot is a camera shot from a medium distance. The dividing line between "long shot" and "medium shot" is fuzzy,
as is the line between "medium shot" and "close-up". In some standard texts and professional references, a full-length view of a human
subject is called a medium shot; in this terminology, a shot of the person from the knees up or the waist up is a close-up shot. In other texts,
these partial views are called medium shots. (For example, in Europe a medium shot is framed from the waist up.)
There is no evident reason for this variation. It is not a distinction caused by, for example, a difference between
TV and film language or 1930s and 1980s language.
Medium shots are relatively good in showing facial expressions but work well to show body language.
Depending where the characters are placed in the shot, a medium shot is used to represent importance and power.

LONG SHOT








LONG SHOT
In photography, film and video, a long shot (sometimes referred to as a full shot or a wide shot) typically shows the entire object or human figure
and is usually intended to place it in some relation to its surroundings. It has been suggested that long-shot ranges usually correspond to approximately
what would be the distance between the front row of the audience and the stage in live theatre. It is now common to refer to a long shot
as a "wide shot" because it often requires the use of a wide-angle lens. When a long shot is used to set up a location and its participants
in film and video, it is called an establishing shot.
A related notion is that of an extreme long shot. This can be taken from as much as a quarter of a mile away, and is generally used as a scene-setting, e
stablishing shot. It normally shows an exterior, eg the outside of a building, or a landscape, and is often used to show scenes of
thrilling action eg in a war film or disaster movie. There will be very little detail visible in the shot, as it is meant to give a general
impression rather than specific information.

Friday, October 9, 2009

Film Speed


Current ISO system
The current
International Standard for measuring the speed of colour negative film is called ISO 5800:1987 from the International Organization for Standardization (ISO). Related standards ISO 6:1993 and ISO 2240:2003 define scales for speeds of black-and-white negative film and color reversal film. This system defines both an arithmetic and a logarithmic scale, combining the previously separate ASA and DIN systems. In the ISO arithmetic scale, corresponding to the ASA system, a doubling of the sensitivity of a film requires a doubling of the numerical film speed value. In the ISO logarithmic scale, which corresponds to the DIN scale, adding 3° to the numerical value that designates the film speed constitutes a doubling of that value. For example, a film rated ISO 200/24° is twice as sensitive as a film rated ISO 100/21°.
Commonly, the logarithmic speed is omitted, and only the arithmetic speed is given; for example, “ISO 100”. Older systems GOST (Russian: ГОСТ) is an arithmetic scale which was used in the former Soviet Union before 1997. It is almost identical to the ASA standard, having been based on a speed point at a density 0.2 above base plus fog, as opposed to the ASA's 0.1. After 1987, the GOST scale was aligned to the ISO scale. GOST markings are only found on pre-1987 photographic equipment (film, cameras, lightmeters, etc.) of Soviet Union manufacture. Conversion from the logarithmic DIN speed S° to the arithmetic ASA speed S, as given by requires the following calculation: and rounding to the nearest standard arithmetic speed in the table below. By simple rearrangement, conversion from arithmetic speed to logarithmic speed is given by
and rounding to the nearest integer. Here the log function is base 10.

Determining film speed
ISO 6:1993 method of determining speed for black-and-white film.
Film speed is found from a plot of
optical density vs. log of exposure for the film, known as the D–log H curve or Hurter–Driffield curve. There typically are five regions in the curve: the base + fog, the toe, the linear region, the shoulder, and the overexposed region. For black and white negative film, the “speed point” m is the point on the curve where density exceeds the base + fog density by 0.1 when the negative is developed so that a point n where the log of exposure is 1.3 units greater than the exposure at point m has a density 0.8 greater than the density at point m. The exposure Hm, in lux-s, is that for point m when the specified contrast condition is satisfied. The ISO arithmetic speed then is Determining speed for color negative film is similar in concept but more complex because it involves separate curves for blue, green, and red. The film is processed according to the film manufacturer’s recommendations rather than to a specified contrast. ISO speed for color reversal film is determined from the middle rather than the threshold of the curve; it again involves separate curves for blue, green, and red, and the film is processed according to the film manufacturer’s recommendations.
Applying film speed
Film speed is used in the
exposure equations to find the appropriate exposure parameters. Four variables are available to the photographer to obtain the desired effect: lighting, film speed, f-number (aperture size), and shutter speed (exposure time). The equation may be expressed as ratios, or, by taking the logarithm (base 2) of both sides, by addition, using the APEX system, in which every increment of 1 is a doubling of exposure, known as a "stop". The effective f-number is proportional to the ratio between the lens focal length and aperture diameter, which is proportional to the square root of the aperture area. 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 f-number factor of the square root of two (approximately 1.4) is also a stop, so lenses are typically marked in that progression: f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc.
Exposure index
Exposure index, or EI, refers to speed rating assigned to a particular film and shooting situation in variance to the film's actual speed. It is used to compensate for equipment calibration inaccuracies or process variables, or to achieve certain effects. The exposure index may simply be called the speed setting, as compared to the speed rating.
For example, a photographer may rate an ISO 400 film at EI 800 and then use
push processing to obtain printable negatives in low-light conditions. The film has been exposed at EI 800.
Another example occurs where a camera's
shutter is miscalibrated and consistently overexposes or underexposes the film; similarly, a light meter may be inaccurate. One may adjust the EI rating accordingly in order to compensate for these defects and consistently produce correctly exposed negatives.[citation needed]
Reciprocity
Upon exposure, the amount of light energy that reaches the film determines the effect upon the emulsion. If the brightness of the light is multiplied by a factor and the exposure of the film decreased by the same factor by varying the camera's
shutter speed and aperture, so that the energy received is the same, the film will be developed to the same density. This rule is called reciprocity. The systems for determining the sensitivity for an emulsion are possible because reciprocity holds. In practice, reciprocity works reasonably well for normal photographic films for the range of exposures between 1/1000 second to 1/2 second. However, this relationship breaks down outside these limits, a phenomenon known as reciprocity failure
Film sensitivity and grain
Main article:
Film grain
Grainy high speed B/W film negative
Film speed is roughly related to
granularity, the size of the grains of silver halide in the emulsion, since larger grains give film a greater sensitivity to light. 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 grainier image. Each grain of silver halide develops in an all-or-nothing way into dark silver or nothing. Thus, each grain is a threshold detector; in aggregate, their effect can be thought of as a noisy nonlinear analog light detector.
Kodak has defined a "Print Grain Index" (PGI) to characterize film grain (color negative films only), based on perceptual just noticeable difference of graininess in prints. They also define "granularity", a measurement of grain using an RMS measurement of density fluctuations in uniformly-exposed film, measured with a microdensitometer with 48 micrometre aperture. Granularity varies with exposure — underexposed film looks grainier than overexposed film.
Use of grain
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.
Marketing anomalies
Some high-speed black-and-white films, such as
Ilford Delta 3200 and Kodak T-MAX P3200, are marketed with film speeds in excess of their true ISO speed as determined using the ISO testing method. For example, the Ilford product is actually an ISO 1000 film, according to its data sheet.The manufacturers do not indicate that the 3200 number is an ISO rating on their packaging. These films can be successfully exposed at EI 3200 (or any of several other speeds) through the use of push processing.

Shutter speed

Factors that affect the total exposure of a photograph include the scene luminance, the aperture size (f-number), and the exposure time (shutter speed); photographers can trade off shutter speed and aperture by using units of stops. A stop up and down on each will halve or double the amount of light regulated by each; exposures of equal exposure value can be easily calculated and selected. For any given total exposure, or exposure value, a fast shutter speed requires a larger aperture (smaller f-number). Similarly, a slow shutter speed, a longer length of time, can be compensated by a smaller aperture (larger f-number).
Slow shutter speeds are often used in low light conditions, extending the time until the shutter closes, and increasing the amount of light gathered. This basic principle of photography, the exposure, is used in film and digital cameras, the image sensor effectively acting like film when exposed by the shutter.
Shutter speed, or more literally exposure time, is measured in seconds, but often marked in reciprocal seconds. A typical exposure time for photographs taken in sunlight is 1/125th of a second, typically marked as 125 on a shutter speed setting dial. 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 used to intentionally blur a moving subject for artistic effect.
Adjustment to the aperture controls the depth of field, the distance range over which objects are acceptably sharp; such adjustments generally need to be compensated by changes in the shutter speed.
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 step 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 standards for shutter speeds are:
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 Each standard increment either doubles the amount of light (longer time) or halves the amount of light (shorter time). For example, if you move from 1 sec to 1/2 second, you have effectively halved the amount of light entering the shutter. This scale can be extended at either end in specialist cameras. Some older cameras use the 2:1 ratio at slightly different values, such as 1/100 s and 1/50 s, although mechanical shutter mechanisms were rarely precise enough for the difference to have any significance.
The term "speed" is used in reference to short exposure times as fast, and long exposure times as slow. Shutter speeds are often designated by the reciprocal time, for example 60 for 1/60 s.
Camera shutters often include one or two other settings for making very long exposures:
B (for bulb) — keep the shutter open as long as the shutter release is held T (for time) — keep the shutter open until the shutter release is pressed again 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 35 mm photographers is that the slowest shutter speed that can be used easily without much blur due to camera shake 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. This rule can be augmented with knowledge of the intended application for the photograph, an image intended for significant enlargement and closeup viewing would require faster shutter speeds to avoid obvious blur. Through practice and special techniques such as bracing the camera, arms, or body to minimize camera movement longer shutter speeds can be used without blur. If a shutter speed is too slow for hand holding, a camera support — usually a tripod — must be used. Image stabilization can often permit the use of shutter speeds 3-4 stops slower (exposures 8-16 times longer).
Shutter priority refers to a shooting mode used in semi-automatic cameras. It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture. This is sometimes referred to as Shutter Speed Priority Auto Exposure, or Tv (time value) mode.
In cinematography, shutter speed is a function of the frame rate and shutter angle. Most motion picture film cameras use a rotating shutter with a shutter angle of 165° or 180°, which leaves the film exposed for about 1/48 or 1/50 second at standard 24 frame/s.
Where E = shutter speed (reciprocal of exposure time in seconds), F = Frames per second, and S = Shutter angle: for E in reciprocal seconds

Wednesday, August 19, 2009

Color Temperature & White balance




Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, and other fields. The color
temperature of a light source is determined by comparing its chromaticity with that of an ideal black-body radiator. The temperature (usually measured in kelvins (K))
at which the heated black-body radiator matches the color of the light source is that source's color temperature; for a black body source, it is directly related to
Planck's law and Wien's displacement law.
Higher color temperatures (5000 K or more) are "cool" (green–blue) colors, and lower color temperatures (2700–3000 K) "warm" (yellow–red) colors.
Because it is the standard against which other light sources are compared, the color temperature of the thermal radiation from an ideal black body radiator is defined
as equal to its surface temperature in kelvin, or alternatively in mired (micro-reciprocal degrees kelvin).[1] For source other than ideal black bodies, the color
temperature of the thermal radiation emitted from it may differ from its actual surface temperature. In an incandescent light bulb the light is of thermal origin and is
very close to that of an ideal black-body radiator.
However, many other light sources, such as fluorescent lamps, emit light primarily by processes other than raising the temperature of a body. This means the emitted
radiation does not follow the form of a black-body spectrum. These sources are assigned what is known as a correlated color temperature (CCT). CCT is the color
temperature of a black body radiator which to human color perception most closely matches the light from the lamp. Because such an approximation is not required for
incandescent light, the CCT for an incandescent light is simply its unadjusted temperature, derived from the comparison to a black body radiator.

The sunAs the sun crosses the sky, it may appear to be red, orange, yellow or white depending on its position. The changing color of the sun over the course of the day is
mainly a result of scattering of light, and is unrelated to black body radiation. The blue color of the sky is not caused by black-body radiation, but rather to
Rayleigh scattering of the sunlight from the atmosphere, which tends to scatter blue light more than red. This phenomenon has nothing to do with the properties of a
black body.
Daylight has a spectrum similar to that of a black body. In professions involving color reproduction, such as photography and publishing, daylight is often approximated
using standard illuminant D50 or D65, as recommended by the CIE.
For colors based on the black body, blue is the "hotter" color, while red is actually the "cooler" color. This is the opposite of the cultural associations that colors
have taken on, with "red" as "hot", and "blue" as "cold". The traditional associations come from a variety of sources, such as water and ice appearing blue, while
heated metal and fire are of a reddish hue. However, the redness of these heat sources comes precisely from the fact that red is the coolest of the visible colors, the
first color emitted as heat increases.
In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An
important goal of this adjustment is to render specific colors – particularly neutral colors – correctly; hence, the general method is sometimes called gray balance,
neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction; generalized versions of color
balance are used to get colors other than neutrals to also appear correct or pleasing.
Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color
reproduction or display. Several aspects of the acquisition and display process make such color correction essential – including the fact that the acquisition sensors
do not match the sensors in the human eye, that the properties of the display medium must be accounted for, and that the ambient viewing conditions of the acquisition
differ from the display viewing conditions.
The color balance operations in popular image editing applications usually operate directly on the red, green, and blue channel pixel values, without respect to
any color sensing or reproduction model. In shooting film, color balance is typically achieved by using color correction filters over the lights or on the camera lens


White Balance
Most digital cameras have a means to select a color correction based on the type of scene illumination, using either manual illuminant selection, or automatic white
balance (AWB), or custom white balance. The algorithm that performs this analysis performs generalized color balancing, known as illuminant adaptation or chromatic
adaptation.
Many methods are used to achieve color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting.
Another option on some cameras is a button which one may press when the camera is pointed at a white card or other neutral object. This "custom white balance" step
captures an image of the ambient light, and this information is helpful in controlling color balance.
There is a large literature on how one might estimate the ambient illumination from the camera data and then use this information to transform the image data. A variety
of algorithms have been proposed, and the quality of these have been debated. A few examples and examination of the references therein will lead the reader to many
others. Examples are Retinex, an artificial neural network or a Bayesian method.


Thursday, August 6, 2009

Key Light


The key light can be "hard" (focused) or "soft" (diffused), and depending on the desired setup can be placed at different angles relative to the subject. When part of the most common setup—three-point lighting—the key light is placed at a 30–60° angle (with the camera marking 0 degrees). In addition to the horizontal angle, the key light can be placed high or low producing different effects. The most common vertical position for the key light is at a 30° degree angle (i.e. slightly above the eye line, the nose should not cast a shadow on the lips).
A key light positioned low appears to distort the actor's features, since most natural or ambient light is normally overhead. A dramatic effect used in horror or comedy cinematography is a key light illuminating the face from below. A high key light will result in more prominent cheek bones and long nose shadows. Marlene Dietrich was famous for demanding that her key light be placed high.
Lighting a sceneUsing just a key light results in a high-contrast scene, especially if the background is not illuminated. A fill light decreases contrast and adds more details to the dark areas of an image. An alternative to the fill light is to reflect existing light or to illuminate other objects in the scene (which in turn further illuminate the subject).
In addition to a key light, a back light may be added to "separate" the subject from the background. When the subject and/or camera are moving or turning around, the key light and back light may change roles.
The key light does not have to directly illuminate the subject: it may pass through various filters, screens, or reflectors. Light passing through tree leaves, window panes, and other obstacles can make a scene more visually interesting, as well as cue the audience to the location of the subject. The key light also does not have to be white light—a colored key (especially when used with fill/back lighting of other colors) can add more emotional depth to a scene than full white alone. In mixed indoor/outdoor daytime scenes, sunlight may appear to be a "warm" white, and indoor lighting to be a "neutral" or artificially-toned white. By contrast, moonlight appears to be "cooler" than indoor lighting.
Lighting choicesIn many cases, the key light is a stage light for indoor scenes, or sunlight for outdoors. A lighting instrument may also be used outdoors to supplement sunlight or as the primary light source with sunlight or skylight serving as fill lighting. Actual lamps, lighting fixtures, can serve as key lights, provided they are of sufficient brightness. They may also appear within the scene as props — in which case they are called "practicals." Similarly, fire, candles and other natural sources of light can be used.