parfocal lens

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• Parfocal lens — A parfocal lens is a lens that stays in focus when magnification/focal length is changed. There is inevitably some amount of focus error, but small enough not to be considered significant.MicroscopyParfocal microscope objectives stay in focus… …   Wikipedia

• parfocal — adjective Etymology: Latin par equal + English focal Date: circa 1886 being or having lenses or lens sets (as eyepieces) with the corresponding focal points all in the same plane • parfocality noun • parfocalize transitive verb …   New Collegiate Dictionary

• Zoom lens — Nikkor 28 200 mm zoom lens, extended to 200 mm at left and collapsed to 28 mm focal length at right A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed… …   Wikipedia

• Varifocal lens — A varifocal lens is a camera lens with variable focal length in which focus changes as focal length (and magnification) changes, as compared to parfocal ( true ) zoom lens, which remains in focus as the lens zooms (focal length and magnification… …   Wikipedia

• Optical microscope — Microscope Uses Small sample observation Notable experiments Discovery of cells Inventor Hans Lippershey Zacharias Jans …   Wikipedia

• Objective (optics) — Several objective lenses on a microscope. In an optical instrument, 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 single lenses or… …   Wikipedia

• August Köhler — Infobox Scientist name = August Köhler |300px caption = August Köhler, ca. 1930 birth date = birth date|1866|3|4|mf=y birth place = Darmstadt, Germany death date = death date and age|1948|3|12|1866|3|4|mf=y death place = Jena, Germany residence …   Wikipedia