The shutter in most motion-picture cameras is a focal plane type and is called a rotary disk shutter. A rotary disk shutter is a disk that has a segment cut out, causing the shutter to have a light and dark cycle as it rotates. Exposure is made when the cutout segment of the shutter passes in front of the film. The film is advanced during the dark cycle

Answered by Shobhit , an ibibo Master, at 2:56 PM on May 11, 2008

a shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as in a movie projector or signal lamp.

Shutters immediately behind the lens were used in some cameras with limited lens interchangeability. Shutters in front of the lens were used in the early days of photography.

Focal-plane shutters are usually implemented as a pair of cloth, metal, or plastic curtains which shield the film from light. 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, so that each section of the film or sensor is exposed for the correct amount of time. The effective exposure time can be much shorter than for central shutters.

Focal plane shutters have the advantages of enabling much shorter exposures, and allowing the use of interchangeable lenses without requiring the expense of a separate shutter for each lens. They have the disadvantage of distorting the images of fast-moving objects: 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.

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.

he time for which a shutter remains open, the exposure time, is determined by a timing mechanism. These were originally mechanical, but since the late twentieth century are mostly electronic.

The exposure time and the effective aperture of the lens must together be such as to allow the right amount 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; sometimes a controlled degree of blur is desired, to give a sensation of movement.

Most shutters generate a signal 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, but is simple with electronic timers and electronic flash units which fire virtually instantaneously. When using a focal-plane shutter with a flash, a photographer will typically operate the shutter at its X-sync speed or slower; however, some electronic flashes can produce a steady pulse compatible with a focal-plane shutter operated at much faster shutter speeds.

Cinematography uses a rotary disc shutter in movie cameras, a continuously spinning disc which conceals the image with a reflex mirror during the intermittent motion between frame exposure. The disc then spins to an open section that exposes the next frame of film while it is held by the registration pin.

Answered by Sharad Singh , an ibibo Master, at 1:59 PM on May 02, 2008

well Raksha,The shutter in most motion-picture cameras is a focal plane type and is called a rotary disk shutter. A rotary disk shutter is a disk that has a segment cut out, causing the shutter to have a light and dark cycle as it rotates. Exposure is made when the cutout segment of the shutter passes in front of the film. The film is advanced during the dark cycle
On motion picture cameras film is exposed as a pie-shaped mirror, called a rotary disc shutter, rotates in front of the film gate. As the mirror spins it reflects the image into the ground glass so that it can be viewed by the camera operator part of the time. The other part of the time the mirror allows the light to pass on to the film. On simple cameras this shutter is fixed and usually semi-circular. On more advanced cameras the shape of the shutter can be adjusted. This shutter setting is referred to as the shutter angle.

Adjusting the shutter angle controls the proportion of time that the film is exposed to light during each frame interval. The angle of the shutter forms a proportion to the time that each frame of film is exposed:

\frac{Shutter Angle}{360^\circ} = \frac{Exposure Time}{Frame Interval}

The primary reason that cinematographers adjust the shutter angle is to control the amount of motion blur that is recorded on each successive frame of film. A tight shutter angle will constrict motion blur. A wide shutter angle will allow it. A 180° shutter angle is considered normal.

Answered by Uttam , an ibibo Master, at 10:12 AM on May 01, 2008

On motion picture cameras film is exposed as a pie-shaped mirror, called a rotary disc shutter, rotates in front of the film gate. As the mirror spins it reflects the image into the ground glass so that it can be viewed by the camera operator part of the time.

Answered by sharda , an ibibo Advisor, at 11:29 PM on April 30, 2008

In photography, a shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as in a movie projector or signal lamp.

Answered by bhanu pratap , an ibibo Citizen, at 5:11 PM on April 23, 2008

In photography, a shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as in a movie projector or signal lamp.

Answered by yogesh , an ibibo Citizen, at 5:07 PM on April 23, 2008

While the vast majority of rotary shutters are naturally used on motion-picture cameras (as well as projectors), there were some still cameras that employed this type of shutter, notably the Univex Mercury and the Olympus Pen F SLR. Both of these cameras were half-frame 35mm cameras (frame size 18 x 24 mm). The rotary shutter proved to be very simple to construct, accurate and reliable in these cameras, though in the case of the Univex it resulted in a very strange "hump" on top of the camera to cover the shutter disk.

Answered by anil kumar , an ibibo Citizen, at 4:58 PM on April 23, 2008

Many video cameras also provide the ability to adjust their shutter. In most cases the camera does not have an actual mechanical shutter. Instead, this adjustment controls the amount of time that the electronic sensor collects light in order to create each successive image. Because electronic cameras do not need to mechanically advance film, it is possible for the shutter to be open for nearly the entire period of each successive frame. At 24 frames per second, it is possible to expose a frame for nearly 1/24th second, achieving longer motion blur otherwise impossible to achieve on film at sync sound speeds.
The term electronic shutter is often used to describe the electronic process of controlling exposure time on a light sensor. The same term is also used in film cameras to refer to a mechanical rotary shutter which can adjust its shutter angle electronically while shooting.

Answered by amit , an ibibo Citizen, at 4:53 PM on April 23, 2008

On most film cameras the shutter angle is changed by removing the lens and adjusting the shutter with a special tool. This cannot be done while the camera is operating. Some cameras such as the Arriflex 435ES can modify their shutter angle during the shot. This is sometimes referred to as an electronic shutter. An electronic shutter can, for one purpose, compensate for the exposure change caused by a speed ramp without changing the aperture and affecting depth of field.
Other types of shutter adjustment such as an out-of-phase shutter, and a fluttering shutter are also possible. Normally the film is held steady in the gate whenever it is exposed to light. Special shutter adjustments allow the film to be exposed while the camera mechanism is actually moving the film to the next frame. In the film Saving Private Ryan, cinematographer Janusz Kaminski used such a shutter adjustment to give his film the look of World War II newsreel photography. Previously, this effect could only be achieved by purposefully mis-adjusting the timing belt of the film advance mechanism in the camera. However, several manufacturers now provide accessories to electronically control the phase relationship of the shutter and film advance mechanisms. One such device is the Timing Shift Box available for the above mentioned ARRI 435 series.

Answered by savesh singh , an ibibo Citizen, at 4:40 PM on April 23, 2008

to expose a pictur as a pie-shaped mirror is called , rotates in front of the film gate. As the mirror spins it reflects the image into the ground glass so that it can be viewed by the camera operator part of the time. The other part of the time the mirror allows the light to pass on to the film. On simple cameras this shutter is fixed and usually semi-circular. On more advanced cameras the shape of the shutter can be adjusted. This shutter setting is referred to as the shutter angle.

Answered by khushvinder , an ibibo Citizen, at 4:01 PM on April 23, 2008