An early (1875) rapid acting shutter by A. A. Pearson of Leeds
In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitivedigital sensor to light in order to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film. The shutter is constructed so that it automatically closes after a certain required time interval. The speed of the shutter is controlled either automatically by the camera based on the overall settings of the camera, manually through digital settings, or manually by a ring outside the camera on which various timings are marked.
The 1911 Cyclopedia of Photography divides shutters into "roller-blind" and "diaphragm" types, corresponding roughly to the modern focal-plane and leaf types.
Camera shutters can be fitted in several positions:
Leaf shutters are usually fitted within a lens assembly (central shutter), or more rarely immediately behind (behind-the-lens shutter) or, even more rarely, in front of a lens, and shut off the beam of light where it is narrow.
Behind-the-lens shutters were used in some cameras with limited lens interchangeability. Shutters in front of the lens, sometimes simply a lens cap that is removed and replaced for the long exposures required, were used in the early days of photography. Other mechanisms than the dilating aperture and the sliding curtains have been used; anything which exposes the film to light for a specified time will suffice.
The time for which a shutter remains open (exposure time, often called "shutter speed") is determined by a timing mechanism. These were originally pneumatic (Compound shutter) or clockwork, but since the late twentieth century are mostly electronic. Mechanical shutters typically had a Time setting, where the shutter opened when the button was pressed and remained open until it was pressed again, Bulb where the shutter remained open as long as the button was pressed (originally actuated by squeezing an actual rubber bulb), and Instantaneous exposure, with settings ranging from 30" to 1/4000" for the best leaf shutters, faster for focal-plane shutters, and more restricted for basic types. The reciprocal of exposure time in seconds is often used for engraving shutter settings. For example, a marking of "250" denotes 1/250". This does not cause confusion in practice.
The exposure time and the effective aperture of the lens must together be such as to allow the right amount of light to reach the film or sensor. Additionally, the exposure time must be suitable to handle any motion of the subject. Usually it must be fast enough to "freeze" rapid motion, unless a controlled degree of motion blur is desired, for example to give a sensation of movement.
Most shutters have a flash synchronization switch to trigger a flash, if connected. This was quite a complicated matter with mechanical shutters and flashbulbs which took an appreciable time to reach full brightness, focal-plane shutters making this even more difficult. Special flashbulbs were designed which had a prolonged burn, illuminating the scene for the whole time taken by a focal plane shutter slit to move across the film. These problems were essentially solved for non-focal-plane shutters with the advent of electronic flash units which fire virtually instantaneously and emit a very short flash.
When using a focal-plane shutter with a flash, if the shutter is set at its X-sync speed or slower the whole frame will be exposed when the flash fires (otherwise only a band of the film will be exposed). Some electronic flashes can produce a longer pulse compatible with a focal-plane shutter operated at much higher shutter speeds. The focal-plane shutter will still impart focal-plane shutter distortions to a rapidly moving subject.
A focal-plane shutter is positioned just in front of the film, in the focal plane, and moves an aperture across the film until the full frame has been exposed. Focal-plane shutters are usually implemented as a pair of light-tight cloth, metal, or plastic curtains. For shutter speeds slower than a certain point (known as the X-sync speed of the shutter), which depends on the camera, one curtain of the shutter opens, and the other closes after the correct exposure time. At shutter speeds faster than the X-sync speed, the top curtain of the shutter travels across the focal plane, with the second curtain following behind, effectively moving a slit across the focal plane until each part of the film or sensor has been exposed for the correct time. The effective exposure time can be much shorter than for central shutters, at the cost of some distortion of fast-moving subjects.
Focal plane shutters have the advantage over central leaf shutters of allowing the use of interchangeable lenses without requiring a separate shutter for each lens. (Leaf shutters behind the lens also allow interchanging the lens using a single shutter.)
They have several disadvantages as well:
Distortion of fast-moving subjects: although no part of the film is exposed for longer than the time set on the dial, one edge of the film is exposed an appreciable time after the other, so that a horizontally moving shutter will, for example, elongate or shorten the image of a car speeding in the same or the opposite direction to the shutter movement.
They are noisier, which is a detriment to candid and nature photography.
Their more complex mechanical structure causes a shorter life-span than other shutter designs.
If a focal-plane shutter camera is left with sunlight falling on the lens (and the mirror up for an SLR), it is possible to burn a hole in the closed curtain of a non-metal shutter.
Camera shake due to the impact of the larger curtains starting and stopping rapidly. Camera designers have learned to overcome SLR mirror-slap by including a mirror lock-up feature in some cameras. This removes the camera-shake from the large slapping mirror inside the camera, but does not prevent camera-shake caused by the shutter mechanism itself. Mirror-lock-up introduces yet another problem: with the mirror locked-up out of the way the optical viewfinder cannot be used for focussing, framing, or exposure metering. Newer[when?] DSLR cameras include a "live preview" where the image from the main imaging sensor is displayed directly on an LCD display, so it is still possible to focus (manually or in newer models by contrast detection) and frame. This prevents most camera shake from the focal-plane shutter, as instead of a first curtain an electronic shutter is used.
Simple leaf shutter
Simple leaf shutter 1. Shutter plate 2. Aperture covered by leaf shutter 3. Aperture during exposure 4. Leaf blade 5. Catch mechanism 6. Butterfly spring
A simple leaf shutter is a type of camera shutter consisting of a mechanism with one or more pivoting metal leaves which normally does not allow light through the lens onto the film, but which when triggered opens the shutter by moving the leaves to uncover the lens for the required time to make an exposure, then shuts.
Simple leaf shutters have a single leaf, or two leaves, which pivot so as to allow light through to the lens when triggered. If two leaves are used they have curved edges to create a roughly circular aperture. They typically have only one shutter speed and are commonly found in basic cameras, including disposable cameras. Some have more than one speed.
Guillotine shutter
In the simplest version of Guillotine shutter a plate with an aperture slides across the lens opening. Simple versions from the 1880s and 1890s were often known as Drop shutters. They worked vertically and were usually powered by a rubber band, a spring or just gravity. Later they were fitted to run horizontally in hand cameras where they were spring powered with spring tension or pneumatic regulation.[1]
Rotating shutter
Simple rotary shutter
Many inexpensive box cameras had a shutter consisting of a round metal disk with a hole punched in it along with a spring-loaded release lever, with the solid disk blocking light from entering the camera. When the shutter release lever is actuated, the spring causes the disk to quickly rotate once so that the hole passes the camera aperture and allows light through for a brief moment. Rotary shutters typically only had one fixed, imprecise shutter speed, although most cameras had a Time setting that would lock the shutter open when the release is actuated, allowing for longer exposures.
Hemispheric
The shutter plate consisted of a part of a sphere integrated to rotate behind the lens. It was a type of shutter found on the Photosphere and other cameras.[2]
Diaphragm shutter
Diaphragm or leaf shutters
One diaphragm shutter opening over another in an Akarex camera
Entries in Cassell's Cyclopedia of Photography, 1911. The terminology diaphragm shutter has since fallen from common use.
A diaphragm or leaf[3] shutter (as distinct from the simple leaf shutter above) consists of a number of thin blades which briefly uncover the camera aperture to make the exposure. The blades slide over each other in a way which creates a circular aperture which enlarges as quickly as possible to uncover the whole lens, stays open for the required time, then closes in the same way.[4] The larger the number of blades, the more accurately circular is the aperture. Flash synchronization is easily achieved with a pair of contacts that close when the shutter is fully open.
Ideally the shutter opens instantaneously, remains open as long as required, and closes instantaneously. This is essentially the case at slower speeds, but as speeds approach their maximum the shutter is far from fully open for a significant part of the exposure time. Effectively the shutter acts as an additional aperture, and may cause an increased depth of field, undesirable if shallow focus is being used creatively. Or it may cause mechanical vignetting if the diaphragm is outside of the lens (like a focal plane shutter or apodization filter).
The term diaphragm shutter has also been used to describe an optical stop with a slit, near the focal plane of a moving-film high-speed camera.[5]
A few types and makers of leaf shutters became very well known. The early Compound shutter had a pneumatic mechanism, with a piston sliding against air resistance in a cylinder. They were quieter at slow speeds than clockwork, but potentially very inaccurate. More accurate clockwork mechanisms then replaced the airbrake, and the German Compur,[3][6] and the later Synchro-Compur, became virtually the standard quality shutter. Later the Japanese Copal shutter was widely adopted in quality equipment. The German Prontor and Japanese Seikosha shutters were also widely used. Up and Down with Compur: The development and photo-historical meaning of leaf shutters, by Klaus-Eckard Riess, translated by Robert "The Professor" Stoddard[3] gives a detailed history and technical description of leaf shutters. The company Compur Monitor was still in business as of 2012[update], but made only gas detection systems.[7] Leaf shutters under the Compur, Copal, and Seiko names are no longer manufactured.[6]
Central shutter
A central shutter is not a type of shutter as such, but describes the position of the shutter: it is typically a leaf shutter (or simple leaf shutter), and located within the lens assembly where a relatively small opening allows light to cover the entire image. Leaf shutters can also be located behind, but near, the lens, allowing lens interchangeability. The alternative to a central or behind-the-lens shutter is a focal-plane shutter.
Interchangeable-lens cameras with a central shutter within the lens body require that each lens has a shutter built into it. In practice most cameras with interchangeable lenses use a single focal plane shutter in the camera body for all lenses, while cameras with a fixed lens use a central shutter. Many medium-format and most large-format cameras, however, have interchangeable lenses each fitted with a central shutter. A few interchangeable-lens cameras have a behind-the-lens leaf shutter. Large-format press cameras often had a focal-plane shutter. Some had both a focal-plane shutter (for lens interchangeability) and a lens with central shutter (for flash synchronisation); one shutter would be locked open.
Film cameras, but not digital cameras, with a central shutter and interchangeable lenses often have a secondary shutter or darkslide to cover the film and allow changing lens in mid-roll without fogging the film.
The main advantages of central and behind-the-lens leaf shutters compared to a focal-plane shutter are:
Flash synchronization is possible at all speeds because the shutter opens fully, unlike a focal-plane shutter sliding a slit relatively slowly across the film for a short effective exposure.
Small size is possible as the shutter is placed where the bundle of rays is narrow, either inside or just behind the lens.
Many versions have no connection between the cocking mechanism and the film advance mechanism, making multiple exposures possible (this can be a disadvantage, as multiple exposures can be produced accidentally if the photographer forgets to advance the film).
Usually much quieter.
More realistic photographs in high speed panning—lateral focal plane shutters compress or elongate the image in such cases.
Longer shutter life.
Some disadvantages of the central shutter are:
For an interchangeable lens system, each lens has to have a shutter built into it.
All leaf shutter speeds are limited by the speed at which the leaves can move: typically 1/500th of a second for a high-specification diaphragm shutter and 1/125th of a second for a simple leaf shutter.
Some versions may have no connection between the cocking mechanism and the film advance mechanism, making accidental multiple exposures a common problem, although this is a feature of camera manufacture rather than the shutter itself.
Electronic shutter
Digital image sensors (both CMOS and CCD image sensors) can be constructed to give a shutter equivalent function by transferring many pixel cell charges at one time to a paired shaded double called frame transfer shutter. If the full-frame is transferred at one time, it is a global shutter. Often the shaded cells can independently be read, while the others are again collecting light.[8] Extremely fast shutter operation is possible as there are no moving parts or any serialized data transfers. Global shutter can also be used for videos as a replacement for rotary disc shutters.
Image sensors without a shaded full-frame double must use serialized data transfer of illuminated pixels called rolling shutter. A rolling shutter scans the image in a line-by-line fashion, so that different lines are exposed at different instants, as in a mechanical focal-plane shutter, so that motion of either camera or subject will cause geometric distortions, such as skew or wobble.[9]
Today, most digital cameras use combination of mechanical shutter and electronic shutter or mechanical shutter solely. Mechanical shutter can accommodate up to 1/16000 seconds (for example the Minolta Dynax/Maxxum/α-9 film camera had a maximum of 1/12000, a record in its era, and the later digital Nikon D1 series were capable of 1/16000), while electronic shutter can accommodate at least 1/32000 seconds, used for many superzoom cameras and currently many Fujifilm APS-C cameras (X-Pro2, X-T1, X100T and others).
Stacked CMOS sensors combine the image sensor itself with ADCs and digital memory in the same package. The readout of these sensors is faster than traditional sensors, because the digitized image is transferred into the digital memory in the sensor itself during readout and only afterwards transferred out of the sensor. This results in an electronic shutter which is as fast as a mechanical focal-plane shutter. Some cameras using stacked sensors, like the Nikon Z 9, completely removed the mechanical shutter. Dynamic range and noise performance are not compromised, because these sensors do not utilize a global shutter.
Shutter lag is the time between the shutter release being pressed and the exposure starting. While this delay was insignificant on most film and some digital cameras, many digital cameras have significant delay, which can be a problem with fast-moving subjects as in sports and other action photography. Release lag of a bridge camera such as the 2010 Pentax X90 is a relatively short 1/50s,[10] or 21 milliseconds (ms). The Canon 50d dSLR is specified at 131 ms lag.[11]
In many cases, autofocus (AF) lag is the root cause of shutter lag. Lower-cost cameras and low-light or low-contrast situations will make the effect more pronounced and it is in these cases that AF lag is more noticed. Most AF systems use contrast to determine focus; in situations where contrast is low, the speed at which the camera can determine the best focus can be quite noticeable. Since most modern cameras will not activate the shutter until autofocus is complete, the result is shutter lag. In these cases, the photographer can switch to manual focus to avoid the delay that is attributable to the AF function.
Shutter cycle
A shutter cycle is the process of the shutter opening, closing, and resetting to where it is ready to open again. The life-expectancy of a mechanical shutter is often expressed as a number of shutter cycles. Most digital cameras save the shutter cycle information along with the photos, which contains valuable information such as shutter speed, aperture, and shutter count.[12] There are multiple websites and applications to access the EXIF data.
Projector shutter
In movie projection, the shutter admits light from the lamphouse to illuminate the film across to the projection screen. To avoid brightness flicker, a double-bladed rotary disc shutter admits light two times per frame of film in 24 fps projection, resulting in 24 * 2 = 48 Hz, which is the lower brightness flicker fusion threshold. For 16fps (most silent films and Regular 8mm) and 18fps (Super 8), a triple-bladed shutter is used instead, as 16 * 3 = 48 Hz and 18 * 3 = 54 Hz.
Shutters are also used simply to regulate pulses of light, with no film being used, as in a signal lamp.
A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured.
In optics, the aperture of an optical system is a hole or an opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image of the aperture and focal length of an optical system determine the cone angle of a bundle of rays that comes to a focus in the image plane.
A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.
A view camera is a large-format camera in which the lens forms an inverted image on a ground-glass screen directly at the film plane. The image is viewed, composed, and focused, then the glass screen is replaced with the film to expose exactly the same image seen on the screen.
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 or "taking lens", while the other is used for the viewfinder system, which is usually viewed from above at waist level.
In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. 1⁄500 of a second will let half as much light in as 1⁄250.
An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the entrance pupil. The f-number is also known as the focal ratio, f-ratio, or f-stop, and it is key in determining the depth of field, diffraction, and exposure of a photograph. The f-number is dimensionless and is usually expressed using a lower-case hooked f with the format f/N, where N is the f-number.
A camera lens is an optical lens or assembly of lenses 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.
A flash is a device used in photography that produces a brief burst of light at a color temperature of about 5,500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the electronic flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern cameras often activate flash units automatically.
In photography, flash synchronization or flash sync is the synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor.
In camera design, a focal-plane shutter (FPS) is a type of photographic shutter that is positioned immediately in front of the focal plane of the camera, that is, right in front of the photographic film or image sensor.
Mamiya Digital Imaging Co., Ltd. is a Japanese company that manufactures high-end cameras and other related photographic and optical equipment. With headquarters in Tokyo, it has two manufacturing plants and a workforce of over 200 people. The company was founded in May 1940 by camera designer Seiichi Mamiya and financial backer Tsunejiro Sugawara.
The Pentax Auto 110 and Pentax Auto 110 Super were fully automatic single-lens reflex cameras manufactured by Asahi Pentax for use with Kodak 110 film cartridges. The Auto 110 was introduced with three interchangeable, fixed focal length lenses in 1978. A further three lenses were added in 1981 to coincide with the release of the Auto 110 Super the following year. The camera system was sold until 1985. The complete system is sometimes known as the Pentax System 10, apparently for its official Pentax name, although most Pentax advertising only uses the camera name or Pentax-110. This model represented the only complete ultraminiature SLR system manufactured for the 110 film format, although several fixed-lens 110 SLRs were sold. The camera system also claims to be the smallest interchangeable-lens SLR system ever created.
A digital single-lens reflex camera is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor.
The science of photography is the use of chemistry and physics in all aspects of photography. This applies to the camera, its lenses, physical operation of the camera, electronic camera internals, and the process of developing film in order to take and develop pictures properly.
The Nikon FE is an advanced semi-professional level, interchangeable lens, 35 mm film, single-lens reflex (SLR) camera. It was manufactured by Nikon in Japan from 1978 to 1983, and was available new from dealer stock until c. 1984. The FE uses a metal-bladed, vertical-travel focal plane shutter with a speed range of 8 to 1/1000 second, plus Bulb, and flash X-sync of 1/125th second. It had dimensions of 89.5 millimetres (3.52 in) height, 142 mm (5.6 in) width, 57.5 mm (2.26 in) depth and 590 grams (21 oz) weight. It was available in two colors: black with chrome trim and all black. As on the FM, its model designation did not appear on the front of the camera, but was engraved as a small "FE" preceding the serial number on the rear of the housing.
The history of the single-lens reflex camera (SLR) begins with the use of a reflex mirror in a camera obscura described in 1676, but it took a long time for the design to succeed for photographic cameras. The first patent was granted in 1861, and the first cameras were produced in 1884, but while elegantly simple in concept, they were very complex in practice. One by one these complexities were overcome as optical and mechanical technology advanced, and in the 1960s the SLR camera became the preferred design for many high-end camera formats.
Live preview is a feature that allows a digital camera's display screen to be used as a viewfinder. This provides a means of previewing framing and other exposure before taking the photograph. In most such cameras, the preview is generated by means of continuously and directly projecting the image formed by the lens onto the main image sensor. This in turn feeds the electronic screen with the live preview image. The electronic screen can be either a liquid crystal display (LCD) or an electronic viewfinder (EVF).
The Kodak Retina Reflex is a discontinued series of four single-lens reflex cameras made by Kodak in Germany between 1957 and 1974, as part of the Kodak Retina line of 35mm film cameras.
The design of photographic lenses for use in still or cine cameras is intended to produce a lens that yields the most acceptable rendition of the subject being photographed within a range of constraints that include cost, weight and materials. For many other optical devices such as telescopes, microscopes and theodolites where the visual image is observed but often not recorded the design can often be significantly simpler than is the case in a camera where every image is captured on film or image sensor and can be subject to detailed scrutiny at a later stage. Photographic lenses also include those used in enlargers and projectors.
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