Several objective lenses on a microscope.

An objective in optics is the lens or mirror in a microscope, telescope, camera or other optical instrument, that receives the first light rays from the object being observed. The objective is also called the object lens, object glass, and objective glass. Image File history File links Size of this preview: 800 × 600 pixels Full resolution (2560 × 1920 pixel, file size: 546 KB, MIME type: image/jpeg) Loupe binoculaire binocular microscope Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are... Image File history File links Size of this preview: 800 × 600 pixels Full resolution (2560 × 1920 pixel, file size: 546 KB, MIME type: image/jpeg) Loupe binoculaire binocular microscope Work by Rama File links The following pages on the English Wikipedia link to this file (pages on other projects are... Table of Opticks, 1728 Cyclopaedia Optics ( appearance or look in ancient Greek) is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. ... A lens. ... Robert Hookes microscope (1665) - an engineered device used to study living systems. ... A telescope (from the Greek tele = far and skopein = to look or see; teleskopos = far-seeing) is an instrument designed for the observation of remote objects. ... Photographic lens One of Canons most popular wide angle lenses - 17-40 f/4 L The zoom lens of the Canon Elph A photographic lens (or more correctly, objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images... See also list of optical topics. ... It has been suggested that this article or section be merged with Electromagnetic radiation. ...

Microscope objectives are typically designed to be parfocal, which means that when one changes from one lens to another on a microscope, the sample stays in focus. Photographic zoom lenses may also be parfocal, so that one can change the magnification without having to refocus. A parfocal lens is a microscope objective or camera lens that stays approximately in focus when the magnification is changed. ... An image that is partially in focus, but mostly out of focus in varying degrees. ... A Canon Inc. ...