split-image

Definition: Type of range-finder in which the image is divided in two: the range is found or focus achieved when the two halves match precisely. * In direct-vision viewfinders each half is produced by a different lens. * In SLR cameras, two prisms lying on the focusing screen and opposed (angled in opposite directions to each other) will divide the image unless the image is focused: strictly, the split-image prism is a focusing aid. * Also known as split field.

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