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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.
Nine-blade iris Pentacon 2.8/135 lens with 15-blade iris Aperture mechanism of Canon 50mm f/1.8 II lens, with five blades In the human eye, the iris (light brown) acts as the diaphragm and continuously constricts and dilates its aperture (the pupil) A 750nm titanium-sapphire laser beam passing through an iris diaphragm, while opening and closing the iris.
The placement of the diaphragm within the lens structure is constrained by the need to achieve even illumination over the whole film plane at all apertures and the requirement to not interfere with the movement of any movable lens element. Typically the diaphragm is situated at about the level of the optical centre of the lens.
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A DSLR with this feature is often known as an HDSLR or DSLR video shooter. [34] The first DSLR introduced with an HD movie mode, the Nikon D90, captures video at 720p24 (1280x720 resolution at 24 frame/s). Other early HDSLRs capture video using a nonstandard video resolution or frame rate. For example, the Pentax K-7 uses a nonstandard
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 ...
However, many inexpensive "pseudo" TLRs are fixed-focus models to save on the mechanical complexity. Most TLRs use leaf shutters with shutter speeds up to 1/500 of a second with a bulb setting. For practical purposes, all TLRs are film cameras, most often using 120 film, although there are many examples which used 620 film, 127 film, and 35 mm ...
[1] As implied by the above, lenses are only directly interchangeable within the mount system for which they are built. Mixing mounting systems requires an adapter, which most often results in compromises such as loss of functionality (e.g. lack of autofocus or automatic aperture control). Furthermore, the adapter may require an additional ...