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Shutter photography Although a range of different shutter devices have been used during the development of the camera only two types have been widely used and remain in use today.
The Leaf shutter or more precisely the in-lens shutter is a shutter contained within the lens structure, often close to the diaphragm consisting of a number of metal leaves which are maintained under spring tension and which are opened and then closed when the shutter is released.
The exposure time is determined by the interval between opening and closing. In this shutter design, the whole film frame is exposed at one time. This makes flash synchronisation much simpler as the flash only needs to fire once the shutter is fully open. The focal-plane shutter operates as close to the film plane as possible and consists of cloth curtains that are pulled across the film plane with a carefully determined gap between the two curtains typically running horizontally or consisting of a series of metal plates typically moving vertically just in front of the film plane.
The focal-plane shutter is primarily associated with the single lens reflex type of cameras, since covering the film rather than blocking light passing through the lens allows the photographer to view through the lens at all times except during the exposure itself.
Covering the film also facilitates removing the lens from a loaded camera many SLRs have interchangeable lenses.
A manually inserted blade known as a dark slide allows the film to be covered when changing lenses or film backs. A blind inside the camera covers the film prior to and after the exposure but is not designed to be able to give accurately controlled exposure times and a leaf shutter that is normally open is installed in the lens.
To take a picture, the leaf shutter closes, the blind opens, the leaf shutter opens then closes again, and finally the blind closes and the leaf shutter re-opens the last step may only short takes model essays for composition 11th when the shutter is re-cocked. Using a focal-plane shutter, exposing the whole film plane can take much longer than the exposure time.
The exposure time does not depend on the time taken to make the exposure over all, only on the difference between the time a specific point on the film is uncovered and then covered up again.
In fact in practice the curtains do not run at a constant speed as they would in an ideal design, obtaining an even exposure time depends mainly on being able to make the two curtains accelerate in a similar manner. When photographing rapidly moving objects, the use of a focal-plane shutter can produce some unexpected effects, since the film closest to the start position of the curtains is exposed earlier than the film closest to the end position.
Typically this can result in a moving object leaving a slanting image. The direction of the slant depends on the direction the shutter curtains run in noting also that as in all cameras the image is inverted and reversed by the lens, i. Focal-plane shutters are also difficult to synchronise with flash bulbs and electronic flash and it is often only possible to use flash at shutter speeds where the curtain that opens to reveal the film completes its run and the film is fully uncovered, before the second curtain starts to travel and cover it up again.
Film formats A wide range of film and plate formats have been used by cameras.
In the early history plate sizes were often specific for the make and model of camera although there quickly developed some standardisation for the more popular cameras. The introduction of roll film drove the standardization process still further so that by the s only a few standard roll films were in use.
These included film providing 8, 12 or 16 exposures, film providing 16 or 24 exposures, film providing 8 or 12 exposures principally in Brownie cameras and 35 mm film providing 12, 20 or 36 exposures — or up to 72 exposures in the half-frame format or in bulk cassettes for the Leica Camera range.
It was used for nearly all film-based professional motion picture production. For amateur use, several smaller and therefore less expensive formats were introduced. Camera accessories[ edit ] Accessories for cameras are mainly for care, protection, special effects and functions.
Battery and sometimes a charger. Some professional SLR could be provided with interchangeable finders for eye-level or waist-level focusing, focusing screenseye-cup, data backs, motor-drives for film transportation or external battery packs.
Tripodmicroscope adapter, cable releaseelectric wire release. Dew shield - Prevents moisture build up on the lens. UV filterCan protect the front element of a lens from scratches, cracks, smudges, dirt, dust and moisture while keeping a minimum impact on image quality.
Camera design history[ edit ] Main article: Photographic plate The earliest cameras produced in significant numbers used sensitised glass plates were plate cameras. Light entered a lens mounted on a lens board which was separated from the plate by an extendible bellows.
Many of these cameras had controls to raise or lower the lens and to tilt it forwards or backwards to control perspective. Focussing of these plate cameras was by the use of a ground glass screen at the point of focus. Because lens design only allowed rather small aperture lenses, the image on the ground glass screen was faint and most photographers had a dark cloth to cover their heads to allow focussing and composition to be carried out more easily.
When focus and composition were satisfactory, the ground glass screen was removed and a sensitised plate put in its place protected by a dark slide. To make the exposure, the dark slide was carefully slid out and the shutter opened and then closed and the dark slide replaced.
Glass plates were later replaced by sheet film in a dark slide for sheet film; adaptor sleeves were made to allow sheet film to be used in plate holders. In addition to the ground glass, a simple optical viewfinder was often fitted.
Cameras which take single exposures on sheet film and are functionally identical to plate cameras were used for static, high-image-quality work; much longer in 20th century, see Large-format camerabelow.Short Takes Plus MyLab Writing -- Access Card Package (12th Edition) Short Takes (11th Edition) Elizabeth Penfield.
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