
To adjust a lens so that it produces the sharpest visual image on a screen, or on a camera film plane etc.
The light from a single object passing through the aperture is converged by a lens to form a cone with the tip forming a single point. If the tip of the cone is precisely on the film plane then the image is ‘in focus’. If the tip of the cone falls either in front or behind the film plane then the object is ‘out of focus’.
The National Film and Sound Archive of Australia acknowledges Australia’s Aboriginal and Torres Strait Islander peoples as the Traditional Custodians of the land on which we work and live and gives respect to their Elders both past and present.