Aperture

In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time).
An optical system typically has many openings, or structures that limit the ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point.
In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example, a 100 centimeter aperture. Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system.
Sometimes stops and diaphragms are called apertures, even when they are not the aperture stop of the system.
The word aperture is also used in other contexts to indicate a system which blocks off light outside a certain region. In astronomy for example, a photometric aperture around a star usually corresponds to a circular window around the image of a star within which the light intensity is summed.

Shutter speed

In still cameras, the term shutter speed represents the time that the shutter remains open when taking a photograph. Along with the aperture of the lens (also called f-number), it determines the amount of light that reaches the film or sensor. Conventionally, the exposure is measured in units of exposure value (EV), sometimes called stops, representing a halving or doubling of the exposure.

Multiple combinations of shutter speed and aperture can give the same exposure: halving the shutter speed doubles the exposure (1 EV more), while doubling the aperture (halving the number) increases the exposure by a factor of 4 (2 EV). For this reason, standard apertures differ by √2, or about 1.4. Thus an exposure with a shutter speed of 1/250 s and f/8 is the same as with 1/500 s and f/5.6, or 1/125 s and f/11.

In addition to its effect on exposure, the shutter speed changes the way movement appears in the picture. Very short shutter speeds can be 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.^[2] Short exposure times are sometimes called "fast", and long exposure times "slow".

Adjustment to the aperture controls the depth of field, the distance range over which objects are acceptably sharp; such adjustments need to be compensated by changes in the shutter speed.

In early days of photography, available shutter speeds were not standardized, though a typical sequence might have been 1/10 s, 1/25 s, 1/50 s, 1/100 s, 1/200 s and 1/500 s. 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:^[3]

• 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

An extended exposure can also allow photographers to catch brief flashes of light, as seen here. Exposure time 15 seconds.

With this scale, each increment roughly doubles the amount of light (longer time) or halves it (shorter time).

Camera shutters often include one or two other settings for making very long exposures:

• B (for bulb) keeps the shutter open as long as the shutter release is held.
• T (for time) keeps 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.

Cinematography

Cinematography is the making of lighting and camera choices when recording photographic images for cinema. It is closely related to the art of still photography. Many additional technical difficulties and creative possibilities arise when the camera and elements of the scene may be in motion.

Cinematography is an art form unique to motion pictures. Although the exposing of images on light-sensitive elements dates back to the early 19th century (Canadian Geographic),^[1] motion pictures demanded a new form of photography and new aesthetic techniques.

In the infancy of motion pictures, the cinematographer was usually also the director and the person physically handling the camera. As the art form and technology evolved, a separation between director and camera operator emerged. With the advent of artificial lighting and faster (more light sensitive) film stocks, in addition to technological advancements in optics and new techniques such as color film and widescreen, the technical aspects of cinematography necessitated a specialist in that area.

Cinematography was key during the silent movie era - no sound apart from background music, no dialogue - the films depended on lighting, acting and set.

In 1919, in Hollywood, the new motion picture capital of the world, one of the first (and still existing) trade societies was formed: the American Society of Cinematographers (ASC), which stood to recognize the cinematographer's contribution to the art and science of motion picture making. Similar trade associations have been established in other countries, too.

The ASC defines cinematography as

a creative and interpretive process that culminates in the authorship of an original work of art rather than the simple recording of a physical event. Cinematography is not a subcategory of photography. Rather, photography is but one craft that the cinematographer uses in addition to other physical, organizational, managerial, interpretive and image-manipulating techniques to effect one coherent process

Film stock

Cinematography can begin with rolls of film or a digital image sensor. Advancements in film emulsion and grain structure provided a wide range of available film stocks. The selection of a film stock was one of the first decisions made in preparing a typical 20th century film production.

Aside from the film gauge selection — 8 mm (amateur), 16 mm (semi-professional), 35 mm (professional) and 65 mm (epic photography, rarely used except in special event venues) — the cinematographer has a selection of stocks in reversal (which, when developed, create a positive image) and negative formats along with a wide range of film speeds (varying sensitivity to light) from ISO 50 (slow, least sensitive to light) to 800 (very fast, extremely sensitive to light) and differing response to color (low saturation, high saturation) and contrast (varying levels between pure black (no exposure) and pure white (complete overexposure).

Advancements and adjustments to nearly all gauges of film created the "super" formats wherein the area of the film used to capture a single frame of an image is expanded, although the physical gauge of the film remains the same. Super 8 mm, Super 16 mm and Super 35 mm all utilize more of the overall film area for the image than their "regular" non-super counterparts.

The larger the film gauge, the higher the overall image resolution clarity and technical quality.

The techniques used by the film laboratory to process the film stock can also offer a considerable variance in the image produced. By controlling the temperature and varying the duration in which the film is soaked in the development chemicals and by skipping certain chemical processes (or partially skipping all of them), cinematographers can achieve very different looks from a single film stock in the laboratory. Some techniques that can be used are push processing, bleach bypass and cross processing.

21st century work mostly uses digital cinematography and has no film stocks, but the cameras themselves can be adjusted in ways that go far beyond the abilities of one particular film stock. They can provide varying degrees of color sensitivity, image contrast, light sensitivity and so on. One camera can achieve all the various looks of different emulsions, although it is heavily argued as to which method of capturing an image is the "best" method. Digital image adjustments (ISO, contrast etc.) are executed by estimating the same adjustments that would take place if actual film were in use, and are thus vulnerable to the cameras sensor designers perceptions of various film stocks and image adjustment parameters.

Filters

Filters, such as diffusion filters or color-effect filters, are also widely used to enhance mood or dramatic effects. Most photographic filters are made up of two pieces of optical glass glued together with some form of image or light manipulation material between the glass. In the case of color filters, there is often a translucent color medium pressed between two planes of optical glass. Color filters work by blocking out certain color wavelengths of light from reaching the film. With color film, this works very intuitively wherein a blue filter will cut down on the passage of red, orange and yellow light and create a blue tint on the film. In black-and-white photography, color filters are used somewhat counter intuitively; for instance a yellow filter, which cuts down on blue wavelengths of light, can be used to darken a daylight sky (by eliminating blue light from hitting the film, thus greatly underexposing the mostly blue sky), while not biasing most human flesh tone. Certain cinematographers, such as Christopher Doyle, are well known for their innovative use of filters. Filters can be used in front of the lens or, in some cases, behind the lens for different effects.

Lens

Lenses can be attached to the camera to give a certain look, feel, or effect by focus, color, etc.

As does the human eye, the camera creates perspective and spatial relations with the rest of the world. However, unlike one's eye, a cinematographer can select different lenses for different purposes. Variation in focal length is one of the chief benefits. The focal length of the lens determines the angle of view and, therefore, the field of view. Cinematographers can choose from a range of wide angle lenses, "normal" lenses and long focus lenses, as well as macro lenses and other special effect lens systems such as borescope lenses. Wide-angle lenses have short focal lengths and make spatial distances more obvious. A person in the distance is shown as much smaller while someone in the front will loom large. On the other hand, long focus lenses reduce such exaggerations, depicting far-off objects as seemingly close together and flattening perspective. The differences between the perspective rendering is actually not due to the focal length by itself, but by the distance between the subjects and the camera. Therefore, the use of different focal lengths in combination with different camera to subject distances creates these different rendering. Changing the focal length only while keeping the same camera position doesn't affect perspective but the angle of view only. A Zoom lens allows a camera operator to change their focal length within a shot or quickly between setups for shots. As prime lenses offer greater optical quality and are "faster" (larger aperture openings, usable in less light) than zoom lenses, they are often employed in professional cinematography over zoom lenses. Certain scenes or even types of filmmaking, however, may require the use of zooms for speed or ease of use, as well as shots involving a zoom move.

As in other photography, the control of the exposed image is done in the lens with the control of the diaphragm aperture. For proper selection, the cinematographer needs that all lenses be engraved with T-Stop, not f-stop, so that the eventual light loss due to the glass doesn't affect the exposure control when setting it using the usual meters. The choice of the aperture also affects image quality (aberrations) and depth of field

Aspect ratio and framing

The aspect ratio of an image is the ratio of its width to its height. This can be expressed either as a ratio of 2 integers, such as 4:3, or in a decimal format, such as 1.33:1 or simply 1.33.

Different ratios provide different aesthetic effects. Standards for aspect ratio have varied significantly over time.

During the silent era, aspect ratios varied widely, from square 1:1, all the way up to the extreme widescreen 4:1 Polyvision. However, from the 1910s, silent motion pictures generally settled on the ratio of 4:3 (1.33). The introduction of sound-on-film briefly narrowed the aspect ratio, to allow room for a sound stripe. In 1932 a new standard was introduced, the Academy ratio of 1.37, by means of thickening the frame line.

For years, mainstream cinematographers were limited to using the Academy ratio, but in the 1950s, thanks to the popularity of Cinerama, widescreen ratios were introduced in an effort to pull audiences back into the theater and away from their home television sets. These new widescreen formats provided cinematographers a wider frame within which to compose their images.

Many different proprietary photographic systems were invented and utilized in the 1950s to create widescreen movies, but one dominates film today: the anamorphic process, which optically squeezes the image to photograph twice the horizontal area to the same size vertical as standard "spherical" lenses.

The first commonly used anamorphic format was CinemaScope, which used a 2.35 aspect ratio, although it was originally 2.55. CinemaScope was used from 1953 to 1967, but due to technical flaws in the design and its ownership by Fox, several third-party companies, led by Panavision's technical improvements in the 1950s, now dominate the anamorphic cine lens market.

Changes to SMPTE projection standards altered the projected ratio from 2.35 to 2.39 in 1970, although this did not change anything regarding the photographic anamorphic standards; all changes in respect to the aspect ratio of anamorphic 35 mm photography are specific to camera or projector gate sizes, not the optical system.

After the "widescreen wars" of the 1950s, the motion-picture industry settled into 1.85 as a standard for theatrical projection in the United States and the United Kingdom. This is a cropped version of 1.37. Europe and Asia opted for 1.66 at first, although 1.85 has largely permeated these markets in recent decades. Certain "epic" or adventure movies utilized the anamorphic 2.39.

In the 1990s, with the advent of high-definition video, television engineers created the 1.78 (16:9) ratio as a mathematical compromise between the theatrical standard of 1.85 and television's 1.33, as it was not practical to produce a traditional CRT television tube with a width of 1.85. Until that point, nothing had ever been originated in 1.78. Today, this is a standard for high-definition video and for widescreen television. Some cinema films are now shot using HDTV cameras.

Lighting

Light is necessary to create an image exposure on a frame of film or on a digital target (CCD, etc.). The art of lighting for cinematography goes far beyond basic exposure, however, into the essence of visual storytelling. Lighting contributes considerably to the emotional response an audience has watching a motion picture.

ಛಾಯಾಗ್ರಹಣ

ಛಾಯಾಗ್ರಹಣ : ಛಾಯಾಗ್ರಹಣದ ಚಿತ್ರ, ಅಥವಾ ವಿದ್ಯುನ್ಮಾನ ಇಮೇಜ್ ಸಂವೇದಕಗಳು ಒಂದು ವಿಕಿರಣ-ಸೂಕ್ಷ್ಮ ಮಧ್ಯಮ ರಂದು ರೆಕಾರ್ಡಿಂಗ್ ವಿಕಿರಣವಾಗಿಸಲ್ಪಟ್ಟ ಚಿತ್ರಗಳು, ಸೃಷ್ಟಿಸುವ ಕಲೆ, ವಿಜ್ಞಾನ, ಮತ್ತು ಆಚರಣೆ. ಛಾಯಾಗ್ರಹಣ ಯುವಿ, ಗೋಚರ ಮತ್ತು ಹತ್ತಿರದ ಐಆರ್ ವರ್ಣಪಟಲದಲ್ಲಿ ಅಗ್ರಗಣ್ಯ ವಿಕಿರಣ ಬಳಸುತ್ತದೆ. [1] ಸಾಮಾನ್ಯ ಉದ್ದೇಶಗಳಿಗಾಗಿ ಪದವನ್ನು ಬೆಳಕಿನ ಬದಲಿಗೆ ವಿಕಿರಣದ ಬಳಸಲಾಗುತ್ತದೆ. ಪ್ರತಿಫಲಿತ ಅಥವಾ ವಸ್ತುಗಳು ಹೊರಸೂಸುವ ಲೈಟ್ ಬೆಳಕು ಸೂಕ್ಷ್ಮ ಪ್ರದೇಶ (ಚಿತ್ರ ಅಥವಾ ಪ್ಲೇಟ್) ಅಥವಾ ಒಂದು ಸಮಯ ಮಾನ್ಯತೆ ಸಮಯದಲ್ಲಿ ಕ್ಯಾಮೆರಾ ಎಂಬ ಸಾಧನದ ಒಂದು ಪಿನ್ ರಂಧ್ರ ಅಥವಾ ಲೆನ್ಸ್ ಮೂಲಕ ಒಂದು FPA ಪಿಕ್ಸೆಲ್ ರಚನೆಯ ಸೆನ್ಸಾರ್ ಮೇಲೆ ನಿಜವಾದ ಚಿತ್ರವನ್ನು ರೂಪಿಸುತ್ತವೆ. ಚಿತ್ರ ಅಥವಾ ಪ್ಲೇಟ್ ಮೇಲೆ ಪರಿಣಾಮವಾಗಿ ತರುವಾಯ ಒಂದು ದೃಶ್ಯ ಚಿತ್ರ (ನಕಾರಾತ್ಮಕ ಅಥವಾ diapositive) ಅಭಿವೃದ್ಧಿ ಒಂದು ಸುಪ್ತ ಚಿತ್ರ, ಇದು. ಕಾಗದದ ಬೇಸ್ ಮೇಲೆ ಚಿತ್ರ ಒಂದು ಮುದ್ರಣ ಎಂದು ಕರೆಯಲಾಗುತ್ತದೆ. FPA ಪಿಕ್ಸೆಲ್ ರಚನೆಯ ಸೆನ್ಸಾರ್ ಮೇಲೆ ಪರಿಣಾಮವಾಗಿ ವಿದ್ಯುನ್ಮಾನ ನಂತರದ ಪ್ರದರ್ಶನ ಅಥವಾ ಸಂಸ್ಕರಣೆಗಾಗಿ (ರ್ಯಾಸ್ಟರ್) ಚಿತ್ರಿಕಾ ಕಡತವನ್ನು ಪರಿಷ್ಕರಿಸಿ ಕಂಪ್ಯೂಟರ್ ಶೇಖರಿತವಾಗಿರುವ ಇದು ಪ್ರತಿ ಪಿಕ್ಸೆಲ್ ಒಂದು ವಿದ್ಯುತ್ ಶುಲ್ಕ. ಛಾಯಾಗ್ರಹಣ ಅನೇಕ ವಾಣಿಜ್ಯ, ವಿಜ್ಞಾನ, ಉತ್ಪಾದನೆ ಬಳಸುತ್ತದೆ (Fi Photolithography), ಕಲೆ, ಮತ್ತು ಮನರಂಜನಾ ಉದ್ದೇಶಕ್ಕಾಗಿ ಹೊಂದಿದೆ.

FocusThe adjustment to place the sharpest focus where it is desired on the subject. Aperture Adjustment of the lens opening, measured as f-number, which controls the amount of light passing through the lens. Aperture also has an effect on depth of field and diffraction – the higher the f-number, the smaller the opening, the less light, the greater the depth of field, and the more the diffraction blur. The focal length divided by the f-number gives the effective aperture diameter.

 Shutter speed  Adjustment of the speed (often expressed either as fractions of seconds or as an angle, with mechanical shutters) of the shutter to control the amount of time during which the imaging medium is exposed to light for each exposure. Shutter speed may be used to control the amount of light striking the image plane; 'faster' shutter speeds (that is, those of shorter duration) decrease both the amount of light and the amount of image blurring from motion of the subject and/or camera.

White balance On digital cameras, electronic compensation for the color temperature associated with a given set of lighting conditions, ensuring that white light is registered as such on the imaging chip and therefore that the colors in the frame will appear natural. On mechanical, film-based cameras, this function is served by the operator's choice of film stock or with color correction filters. In addition to using white balance to register natural coloration of the image, photographers may employ white balance to aesthetic end, for example white balancing to a blue object in order to obtain a warm color temperature.

Metering Measurement of exposure so that highlights and shadows are exposed according to the photographer's wishes. Many modern cameras meter and set exposure automatically. Before automatic exposure, correct exposure was accomplished with the use of a separate light metering device or by the photographer's knowledge and experience of gauging correct settings. To translate the amount of light into a usable aperture and shutter speed, the meter needs to adjust for the sensitivity of the film or sensor to light. This is done by setting the "film speed" or ISO sensitivity into the meter.

ISO speed Traditionally used to "tell the camera" the film speed of the selected film on film cameras, ISO speeds are employed on modern digital cameras as an indication of the system's gain from light to numerical output and to control the automatic exposure system. The higher the ISO number the greater the film sensitivity to light, whereas with a lower ISO number, the film is less sensitive to light. A correct combination of ISO speed, aperture, and shutter speed leads to an image that is neither too dark nor too light, hence it is 'correctly exposed,' indicated by a centered meter.

Autofocus point On some cameras, the selection of a point in the imaging frame upon which the auto-focus system will attempt to focus. Many Single-lens reflex cameras (SLR) feature multiple auto-focus points in the viewfinder.