page_title: Objective (optics)
section_title: Photography and imaging
hierarchical_section_title: Objective (optics) / Types / Photography and imaging
caption_attribution_description: English: This image shows a "Canon EF 50mm f1.4 USM" lens.
context_page_description: In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a single lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses.
context_section_description: Camera lenses (usually referred to as "photographic objectives" instead of simply "objectives") need to cover a large focal plane so are made up of a number of optical lens elements to correct optical aberrations. Image projectors (such as video, movie, and slide projectors) use objective lenses that simply reverse the function of a camera lens, with lenses designed to cover a large image plane and project it at a distance onto another surface.
caption: Camera photographic objective, focal length 50 mm, aperture 1:1.4
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