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The centre of the diaphragm's aperture coincides with the optical axis of the lens system. Most modern cameras use a type of adjustable diaphragm known as an iris diaphragm, and often referred to simply as an iris. See the articles on aperture and f-number for the photographic effect and system of quantification of varying the opening in the ...
Rotating the plate would bring an appropriate sized hole in front of the lens. All modern lenses use a multi-leaf diaphragm so that at the central intersection of the leaves a more or less circular aperture is formed. Either a manual ring, or an electronic motor controls the angle of the diaphragm leaves and thus the size of the opening.
The Pentamatic featured an automatic stop-down diaphragm (offered only with the Auto Yashinon 50mm/1.8 lens), instant-return mirror, a fixed pentaprism, and a mechanical focal-plane shutter with speeds of 1-1/1000 second, along with additional interchangeable lenses.
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.
Aperture priority is a semi-automatic shooting mode used in cameras. It permits the photographer to select an aperture setting and let the camera decide the shutter speed and sometimes also ISO sensitivity for the correct exposure. This is also referred to as Aperture Priority Auto Exposure, A mode, AV mode (aperture-value mode), or semi-auto ...
Compared with some low-cost cameras that provide an optical viewfinder that uses a small auxiliary lens, the DSLR design has the advantage of being parallax-free: it never provides an off-axis view. A disadvantage of the DSLR optical viewfinder system is that when it is used, it prevents using the LCD for viewing and composing the picture.
The first Minolta SLRs were marketed with SR- model numbers starting from 1958 with the Minolta SR-2, which featured semi-automatic diaphragm operation with Auto-Rokkor lenses: winding the film advance lever opened the diaphragm and cocked the shutter; when the shutter was released, the iris would stop down to the selected aperture.
For example, as of 2008, Nikon cameras allow one to set the maximum and minimum ISO sensitivities, and slowest shutter speed that will be used in automatic modes, [4] while Canon cameras will select within the fixed range of ISO 400–ISO 800 in Auto ISO mode. In Nikon cameras, the Auto ISO mode first adjusts the shutter speed, keeping ISO at ...