Technique for selecting lens aperture size for a fill flash expo

Details Technique for selecting lens aperture size for a fill flash expo Technique for selecting lens aperture size for a fill flash expo

1990-09-20

1992-03-24

Perkey, W. B.

354421, G03B 716, G03B 728, G03B 1505

Patent

active

050992686

ABSTRACT:
Apparatus, and an accompanying method, for use in a photographic camera for determining a lens aperture value for use during a fill flash exposure of a scene wherein the aperture value will impart a sufficient depth-of-field to a photographed image of the scene to capture both near and distant (background) subjects therein with pre-defined, typically ISO normal, exposures. Specifically, minimum and maximum aperture limit values are first determined from the permissible fastest and slowest shutter speeds that can be used to provide an ISO normal exposure of the distant subject. The fastest shutter speed is the fastest shutter speed to which a flash unit in use can be synchronized, while the slowest shutter speed is governed by the focal length of the lens in use. Given these maximum and minimum aperture limit values, the lens aperture to use for the fill flash exposure is determined as that which, based upon the distance of the near subject to the camera and a guide number of the flash unit, will provide an ISO normal exposure of the near subject and is equal to either the maximum or minimum aperture limit value or lies between these two limit values.

REFERENCES:
patent: 3843255 (1974-10-01), Cole
patent: 3888580 (1975-06-01), Amano et al.
patent: 3917395 (1975-11-01), Ogawa
patent: 4092067 (1978-05-01), Grossman
patent: 4100424 (1978-07-01), Akimoto et al.
patent: 4101216 (1978-07-01), Grossman
patent: 4103307 (1978-07-01), Shinoda et al.
patent: 4154523 (1979-05-01), Rising et al.
patent: 4168120 (1979-09-01), Freier et al.
patent: 4182560 (1980-01-01), Oguchi et al.
patent: 4279505 (1981-07-01), Ursprung et al.
patent: 4309089 (1982-01-01), Harvey
patent: 4339517 (1982-07-01), Akimoto
patent: 4345825 (1982-08-01), Matteson et al.
patent: 4429969 (1984-02-01), Saegusa
patent: 4598986 (1986-07-01), Shiratori et al.
patent: 4769666 (1988-09-01), Kumakura
patent: 4772910 (1988-09-01), Fields
patent: 4785323 (1988-11-01), Bell
patent: 4801964 (1989-01-01), Desormeaux
patent: 4812872 (1989-03-01), Desormeaux
D. M. Zwick, "The Technical Basis of Photographic Speed Determination, or What is a Normal Exposure?", SMPTE Journal, Aug. 1979, vol. 88, No. 8, pp. 533-537.
"American National Standard for General-Purpose Photographic Exposure Meters (Photoelectric Type) ANSI PH 3.49-1971", American National Standards Institute, 1971.
"American National Standard for Colour Negative Films for Still Photography--Determination of ISO Speed ANSI PH 2.27-1988", American National Standards Institute, 1988.
"American National Standard for Photography--Photographic Exposure Guide ANSI 2.7-1986", American National Standards Institute 1986.
L. Stroebel et al., Photographic Materials and Processes (.RTM. 1986: Focal Press; Boston, Mass.), specifically pp. 42-56.

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