发明名称 Variable angle aperture card
摘要 A variable angle aperture card includes an elongated flat rule foldable compactly and unfolded to provide a horizontal rule with a longitudinal slot with a slide member having a foldable vertically positionable aperture card thereon with a generally rectangular viewing opening therein of a standard photographic print size, which card is slidably adjustable in the slot. Degree of Acceptance and Equivalent Lens Focal Length scales are adhered to the rule on either side of the slot, so that the aperture card is adjustable to a position thereon properly framing the subject, whereat the photographer reads from the scales the angle of view for different camera formats, and determines which lens must be used to photograph the subject from the position at which the framing was made. The combined rule and aperture card may be folded flat for transportation and storage.
申请公布号 US4177573(A) 申请公布日期 1979.12.11
申请号 US19780913460 申请日期 1978.06.07
申请人 BOSTON, JAMES D III 发明人 BOSTON, JAMES D III
分类号 G03B17/56;(IPC1-7):G01C3/00 主分类号 G03B17/56
代理机构 代理人
主权项
地址