Optical filter suitable for portrait photography
AssigneeMinolta Camera Kabushiki Kaisha
InventorsSouichi Kubo, Yukio Okano
Life of this patent
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Abstract
An improved soft focus optical filter is provided and comprises a plurality of effective filter areas on a transparent substrate. The filter areas are designed specifically to modify the modulation transfer function of the filter so that a selective soft focus effect is achieved only for transmitted green light.
Claims5
An optical filter for use with a sharp imaging lens, comprising a transparent substrate and a plurality of transparent minute spots disposed at random on said substrate for producing a phase difference between a wave front transmitted through said spots and that transmitted through the portion of the substrate other than said spots, said phase difference .delta. satisfying the following condition for producing a selective soft focus effect only for green light transmitted through said filter:
- ##EQU6## wherein m is an integer selected from 1, 2, 3 and 4, and .lambda.G is a design wavelength selected within the green wavelength range.
Dependencies are inferred from the claim text.