Difference between revisions of "PAD"
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With the 1959 appearance of the [[Nikon F]] and other Japanese cameras offering internally-coupled, instant-reopen diaphragms, the popularity of the PAD approach soon waned. | With the 1959 appearance of the [[Nikon F]] and other Japanese cameras offering internally-coupled, instant-reopen diaphragms, the popularity of the PAD approach soon waned. | ||
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Revision as of 13:23, 23 November 2013
Glossary Terms
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| External diaphragm plunger (see another view) of 58mm f/2.0 Jena Biotar, aligned with shutter release of Exakta VX500 image by Süleyman Demir (Image rights) |
In reference to lenses, PAD means "pressure activated diaphragm." It is also known as APD for "automatic preset diaphragm." This was a mechanism seen in some 1950s lenses for Exakta, Miranda, and others, where a small arm protruding from the lens piggybacks overtop the shutter release on the front of a camera body. Finger pressure on its plunger closes down the lens diaphragm to the aperture selected on the f/stop ring, just before the shutter release is tripped.
With the 1959 appearance of the Nikon F and other Japanese cameras offering internally-coupled, instant-reopen diaphragms, the popularity of the PAD approach soon waned.
