Difference between revisions of "Instant-return mirror"
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| − | An '''instant-return mirror''' is a mirror in the [[viewfinder|reflex viewfinder]] of an [[SLR]] that automatically returns to the viewing position after an exposure, and so restoring the view through the viewfinder | + | An '''instant-return mirror''' is a mirror in the [[viewfinder|reflex viewfinder]] of an [[SLR]] that automatically returns to the viewing position after an exposure, and so restoring the view through the viewfinder. |
| − | An SLR mirror sits in the light path, in front of the film plane; to take a shot it must move out of the way, which blacks out the viewfinder. | + | An SLR mirror sits in the light path, in front of the film plane; to take a shot it must move out of the way, which blacks out the viewfinder. In many early SLRs, the mirror had to be returned — and the viewfinder restored — manually. Some models provided a so-called '''quick-return mirror''', which returns when the release button is raised, independently of the shutter cycle. Such systems were used on the [[Reflex-Korelle]] or [[Praktiflex]], and on many older large-format SLRs. They relied on gravity or were driven by a spring, and required to keep the button pressed until the exposure is completed. |
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| + | True instant-return mirrors are controlled by the shutter mechanism, and automatically returns after the shutter is fully closed, whatever the position of the release button. It was first introduced by [[Pentax|Asahi Kōgaku]] on the [[Asahiflex|Asahiflex II]] in 1954. The introduction of reliable instant-return mirror mechanisms and the subsequent elimination of the "mirror blackout" was an important step in the acceptance of SLRs by a wide public. | ||
[[Category: Camera parts]] | [[Category: Camera parts]] | ||
[[Category: Viewing system]] | [[Category: Viewing system]] | ||
Revision as of 14:27, 1 June 2009
An instant-return mirror is a mirror in the reflex viewfinder of an SLR that automatically returns to the viewing position after an exposure, and so restoring the view through the viewfinder.
An SLR mirror sits in the light path, in front of the film plane; to take a shot it must move out of the way, which blacks out the viewfinder. In many early SLRs, the mirror had to be returned — and the viewfinder restored — manually. Some models provided a so-called quick-return mirror, which returns when the release button is raised, independently of the shutter cycle. Such systems were used on the Reflex-Korelle or Praktiflex, and on many older large-format SLRs. They relied on gravity or were driven by a spring, and required to keep the button pressed until the exposure is completed.
True instant-return mirrors are controlled by the shutter mechanism, and automatically returns after the shutter is fully closed, whatever the position of the release button. It was first introduced by Asahi Kōgaku on the Asahiflex II in 1954. The introduction of reliable instant-return mirror mechanisms and the subsequent elimination of the "mirror blackout" was an important step in the acceptance of SLRs by a wide public.
