Like aperture settings, exposure times increment in powers of two. However, shorter exposure times require more light to produce a properly exposed image, so shortening the exposure time is not always possible. Very short exposure times can capture fast-moving action and eliminate motion blur. To prevent this, shorter exposure times can be used. ![]() These long exposure times often resulted in blurry images, as a single object is recorded in multiple places across a single image for the duration of the exposure. In the early stages of photography, exposures were often several minutes long. ![]() Typical exposure times can range from one second to 1/1,000 of a second, though longer and shorter durations are not uncommon. The duration for which the shutter is open is called the shutter speed or exposure time. In movie cameras, a rotary shutter opens and closes in sync with the advancement of each frame of film. Electronic shutters either record data from the entire sensor simultaneously (a global shutter) or record the data line by line across the sensor (a rolling shutter). Ī digital camera may use a mechanical or electronic shutter, the latter of which is common in smartphone cameras. ![]() Covering the film also facilitates removing the lens from a loaded camera, as many SLRs have interchangeable lenses. The focal-plane shutter is typically used in single-lens reflex (SLR) cameras, since covering the film (rather than blocking the light passing through the lens) allows the photographer to view the image through the lens at all times, except during the exposure itself. The curtains or plates have an opening that is pulled across the film plane during exposure. This shutter operates close to the film plane and employs metal plates or cloth curtains with an opening that passes across the light-sensitive surface. More commonly, a focal-plane shutter is used. In this shutter, the metal shutter blades travel vertically. What is acceptably in focus is determined by the circle of confusion, the photographic technique, the equipment in use and the degree of magnification expected of the final image. A narrow aperture results in a high depth of field, meaning that objects at many different distances from the camera will appear to be in focus. This depth of field increases as the aperture closes. The wider opening at lower f-stops narrows the range of focus so the background is blurry while the foreground is in focus. The light entering the camera is halved with each increasing increment. The smaller the f-stop, the more light is allowed to enter the lens, increasing the exposure. Īs the aperture is adjusted, the opening expands and contracts in increments called f-stops. The size of the aperture can be set manually, by rotating the lens or adjusting a dial or automatically based on readings from an internal light meter. Typically located in the lens, this opening can be widened or narrowed to alter the amount of light that strikes the film or sensor. Light enters the camera through an aperture, an opening adjusted by overlapping plates called the aperture ring. ![]() The first permanent photograph was made in 1825 by Joseph Nicéphore Niépce. The modern photographic camera evolved from the camera obscura. The word camera comes from camera obscura, which is Latin for "dark chamber" and refers to the original device used to project a 2D image onto a flat surface. Similar artistic fields in the moving-image camera domain include film, videography, and cinematography. Captured images may be reproduced later through processes such as digital imaging or photographic printing. The still image camera is a key instrument in the art of photography. Cameras have various mechanisms to control how light falls onto the light-sensitive surface, including lenses that focus the light and a shutter that determines the amount of time the photosensitive surface is exposed to the light. At a basic level, most cameras consist of a sealed box (the camera body), with a small hole (the aperture) that allows light to pass through and capture an image on a light-sensitive surface (usually a digital sensor or photographic film). Most cameras can capture 2D images, while some more advanced models can capture 3D images. A camera is an optical instrument that captures images.
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