focusing


focusing

optics
also called  ocular accommodation  
 ability of the lens to alter its shape to allow objects to be seen clearly.

 In humans, the forward surface of the lens is made more convex for seeing objects up close. At the same time, the pupil becomes smaller, and the two eyes (eye, human) turn inward (i.e., cross or converge) to the point that their gaze is fixed on the object. The capsule, or envelope enclosing the lens of the eye, is attached by suspensory ligaments (ligament) (called zonular fibres) to the ringlike ciliary muscle that encircles the lens. The inside diameter of this muscle is greatest when the muscle is relaxed and smallest when the muscle is contracted. Thus, when the gaze is fixed on a distant object, as when a camera is set at infinity, the ciliary muscle (ciliaris muscle) relaxes, the muscle's inside diameter is increased, more pull is exerted on the lens by the ligaments, and the front surface of the lens is flattened. When near objects are viewed, the ciliary muscle contracts, the ligaments relax, and the lens, being elastic, bulges in front and gains more curvature. This increased curvature enhances the focusing power of the lens and brings the nearer object to better focus on the retina. This process, known as accommodation, is controlled by parasympathetic fibres of the third (oculomotor) cranial nerve. As a person ages, the lens hardens and slowly loses its ability to change shape and bring near objects into better focus. This condition is called presbyopia and generally becomes evident after age 40.

Daniel M. Albert David M. Gamm
 

* * *


Universalium. 2010.

Look at other dictionaries:

  • Focusing — beschreibt den Kernprozess[1] und die Fähigkeit[2] zu persönlicher Entwicklung und Veränderung. Gleichzeitig stellt Focusing Modelle zur Verfügung, die diesen Prozess und seine Bedingungen und methodischen Schritte lehr und lernbar machen.… …   Deutsch Wikipedia

  • Focusing — is a naturally occurring human process carefully observed and made teachable by philosopher and psychotherapist Eugene Gendlin. Through his work, Gendlin brought the concepts of Focusing to the attention of psychotherapists and developed a… …   Wikipedia

  • focusing — focusing, focussing focussing . 1. the concentration of attention or energy on something. Syn: focus, focussing. [WordNet 1.5] 2. the act of bringing into focus. Syn: focalization, focalisation. [WordNet 1.5] …   The Collaborative International Dictionary of English

  • Focusing — Le focusing est une démarche initiée par Eugène Gendlin, philosophe et psychologue américain, dans la tradition de l’approche humaniste et expérientielle, centrée sur la personne de Carl Rogers. Sommaire 1 Méthode 2 Annexes 2.1 Articles connexes …   Wikipédia en Français

  • Focusing — Focus Fo cus, v. t. [imp. & p. p. {Focused}; p. pr. & vb. n. {Focusing}.] To bring to a focus; to focalize; as, to focus a camera. R. Hunt. [1913 Webster] …   The Collaborative International Dictionary of English

  • Focusing — Fo|cu|sing [ foʊkəsɪŋ], das; s [engl. focusing = das Bündeln, zu: to focus = bündeln, zu: focus, ↑ Fokus]: psychotherapeutisches Verfahren der Introspektion, das der Aufdeckung unbewusster Konflikte u. Motivationen dient …   Universal-Lexikon

  • Focusing — Fo|cu|sing [ foukəsiŋ] das; s <aus engl. focusing »das Bündeln« zu to focus »bündeln«> psychotherapeutisches Verfahren der ↑Introspektion, das der Aufdeckung unbewusster Konflikte u. Motivationen dient …   Das große Fremdwörterbuch

  • focusing — fokusavimas statusas T sritis automatika atitikmenys: angl. focusing vok. Bündelung, f; Fokussierung, f rus. фокусировка, f pranc. focalisation, f …   Automatikos terminų žodynas

  • focusing — fokusavimas statusas T sritis fizika atitikmenys: angl. focusing vok. Fokussieren, n; Fokussierung, f rus. фокусирование, n; фокусировка, f pranc. focalisation, f …   Fizikos terminų žodynas

  • focusing — fokusuotė statusas T sritis fizika atitikmenys: angl. focusing vok. Fokussieren, n; Fokussierung, f rus. фокусирование, n; фокусировка, f pranc. focalisation, f …   Fizikos terminų žodynas


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.