TTL Focus detecting device for single-lens reflex camera
US4571047A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 7, 1984 |
| Grant date | Feb 18, 1986 |
| Priority date | — |
| Expiry date | Jun 7, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/32
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus detecting device for use with a single-lens reflex camera in which chromatic aberration of an infrared beam used for focusing is corrected. When the brightness of the image to be photographed is sufficiently high, a beam of visible light is used for focusing, while when the brightness is not sufficiently high, an infrared beam is employed. In the latter case, a chromatic aberration correction signal is employed to correct the focus detection signal so that the focused position as indicated by that signal coincides with that in the case of the visible beam for the same distance to the object. The chromatic aberration correction signal is preferably produced in response to a resistor or the like mounted on the lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.