Electronic strobe flash apparatus for automatic fill-in and full-flash
US4331400A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1980 |
| Grant date | May 25, 1982 |
| Priority date | — |
| Expiry date | Aug 11, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2215/05
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A quenchable electronic strobe flash unit has a light-responsive integrating circuit for causing the light emitted by a flashtube to be terminated when the integrating circuit senses a predetermined amount of light. A light-level sensing circuit measures the intensity of the ambient light. A threshold-setting circuit, responsive to the sensing circuit, causes the amount of light needed to be sensed by the integrating circuit for terminating the flash in bright ambient light to be, for example, twenty-five percent of the amount of light required to be sensed for terminating the flash in low ambient light. Thus, for subjects within the maximum range of the flash, when ambient light is relatively low, a desired exposure is due primarily to flash light, and when ambient light is relatively high, a selected portion of the desired exposure is attributable to flash light which is, for example, twenty-five percent of the full-flash light output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.