Definition
Focalization is the manner of representation of a narrative. It refers to the perspective through which a narrative is presented.The term used in modern narratology for‘point of view’; that is, for the kind of perspective from which the events of a story are witnessed. Events observed by a traditional omniscient narrator are said to be non‐focalized, whereas events witnessed within the story's world from the constrained perspective of a single character are ‘internally focalized’. The nature of a given narrative's focalization is to be distinguished from its narrative ‘voice’, as seeing is from speaking.

In another words, “Based on the relationship between the focalizer and the focalized, focalization is the product of what the focalizer sees and that which is being seen in addition to their distance from or proximity to the narrator. The relationship between these three creates the nature of the focalization. Whereas the spatial position of the camera determines the focalization of a film, the spatial relation between the narrator, the focalizer and the focalized determines the focalization of a story; the focalization, like the camera, shifts from the perspective of the narrator to another character and to another--resulting in a plurality of perspectives and orientations toward the events in the narrative.”(1)

Origin
Focalization is a term coined by the French narrative theorist Gerard Genette. He introduced the term “focalization” as a replacement for “perspective” and “point of view”. He considers it to be more or less synonymous with these terms, describing it as a mere “reformulation” ([Genette, Gérard ([1983] 1988). Narrative Discourse Revisited. Ithaca: Cornell UP.1983] 1988: 65)(2) and “general presentation of the standard idea of ‘point of view’”. This, however, is an underestimation of the conceptual differences between focalization and the traditional terms.

Types of Focalization
There are three types or degrees of focalization—zero focalization, internal focalization and external focalization.“The first term [zero focalization] corresponds to what English-language criticism calls narrative with omniscient narrator and Pouillon ‘vision from behind,’ and which Todorov symbolizes by the formula Narrator > Character (where the narrator knows more than the character, or more exactly, says more than any of the characters knows). In the second term [internal focalization], Narrator = Character (the narrator says only what a given character knows); this is narrative with ‘point of view’ after Lubbock, or with ‘restricted field’ after Blin; Pouillon calls it ‘vision with.’ In the third term [external focalization], Narrator < Character (the narrator says less than the character knows); this is the ‘objective’ or ‘behaviorist’ narrative, what Pouillon calls ‘vision from without’” ([Genette, Gérard ([1972] 1980). Narrative Discourse. An Essay in Method. Oxford: Blackwell.1972] 1980: 188–89)(3).
Zero focalization: the narrator is omniscient and outside the story. He moves freely in time and space, inside and outside the characters’ minds, and is often not materialized by any physical presence. This narrator may pretend to be transparent and non-existent (in which case he is more a ‘it’ than a ‘he’ or a ‘she’).

Internal focalization: contrary to the previous mode, it excludes external point of view, and requires that the focalizer should be physically materialized. The point of view will commonly be that of one of the characters, who may be an active participant in the story, or a mere observer or witness. The character thus becomes the focalizer of the narrative, i.e. the events are perceived through his/her eyes – generally in the first person singular (‘I’), but not necessarily. Either this character, if speaking of past events, has a global and synthetic view of the story (he/she now knows all the facts and is now in a position to analyze the motives of the other participants), in which case he/she may act as omniscient narrator, or for various reasons he/she has no access to a global understanding of the situation, in which case his/her field of vision is restricted or limited.

External focalization: this narrative technique is rather unusual, even in literature, and was used mostly by American writers in the 1930s and by French novelists of the ‘Nouveau Roman’ school in the 1950s and 1960s.


Study
Genette’s theory about focalization was regarded as a considerable advance on the previous paradigm of perspective or point of view, and the focalization has been widely adopted. Genette himself claims that his term is “preferable because it is less visual and metaphorical than the traditional ones” ([Genette, Gérard ([1972] 1980). Narrative Discourse. An Essay in Method. Oxford: Blackwell.1972] 1980: 189).

However, there were some critics confused of the question “who sees and who speaks”, such as Bal and Finney. Finney states it as follows: “‘Focalization’ is a term coined by Gérard Genette to distinguish between narrative agency and visual mediation, i.e. focalization. ‘Point of View’ confuses speaking and seeing, narrative voice and focalization. Hence the need for Genette’s term” (Finney, Brian (1990). “Suture in Literary Analysis.” LIT: Literature Interpretation Theory 2, 131–44.1990: 144)(4).
It was studied and emphasized in different ways according to different people. Füger, for example, explains that internal and external focalization can be distinguished by the “situation of the agent of the process of perception” (Füger, Wilhelm (1993)(5).

"A characteristic instance of the reinterpretation of focalization in terms of point of view is a change of preposition in the English translation of Genette’s study: “[L]e mode narratif de la Recherche est bien souvent la focalisation interne sur le héros. he narrative mood of the Recherche is very often internal focalization through the hero. Narrative Discourse. An Essay in Method. Oxford: Blackwell.1972] 1980: 199). The rendering of sur as through speaks volumes. It seems that the translator is under the spell of the point-of-view paradigm. Instead of thinking about focalization as a selection of or a focusing on a particular region of the storyworld—in this case the mind of the protagonist—the translator regards this mind as a kind of window through or from which the world is perceived."(6)
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Bal revisized Genette’s theory on deletions such as “external focalization,” it also contains additions, notably the “focalizer,” i.e. the “agent that sees” in a given focalization (Bal [Bal, Mieke ([1985] 1997). Narratology: Introduction to the Theory of Narrative. Toronto: U of Toronto P.1985] 1997: 146)(7). This concept has spawned a considerable amount of controversy, including a more specific debate about the question of whether narrators can be focalizers.

The auguments and confusions on focalization misleaded some concepts but also encouraged the development."Focalization is hardly so much superior to point of view that the old term can be discarded. Niederhoff (Niederhoff, Burkhard (2001). “Fokalisation und Perspektive: Ein Plädoyer für friedliche Koexistenz.” Poetica 33, 1–21.2001) compares the meanings and merits of the terms, making a case for peaceful coexistence of and complementarity between the two. There is room for both because each highlights different aspects of a complex and elusive phenomenon. Point of view seems to be the more powerful metaphor when it comes to narratives that attempt to render the subjective experience of a character; stating that a story is told from the point of view of the character makes more sense than to claim that there is an internal focalization on the character. Focalization is a more fitting term when one analyses selections of narrative information that are not designed to render the subjective experience of a character but to create other effects such as suspense, mystery, puzzlement, etc. If focalization theory is to make any progress, an awareness of the differences between the two terms and of their respective strengths and weaknesses is indispensable."(8)

References
(1).http://narrative.georgetown.edu/wiki/index.php/Focalization#References

(2)Genette, Gérard ([1983] 1988). Narrative Discourse Revisited. Ithaca: Cornell UP.

(3)Genette, Gérard ([1972] 1980). Narrative Discourse. An Essay in Method. Oxford: Blackwell.

(4)Finney, Brian (1990). “Suture in Literary Analysis.” LIT: Literature Interpretation Theory 2, 131–44.

(5)Füger, Wilhelm (1993). “Stimmbrüche: Varianten und Spielräume narrativer Fokalisation.”

(6)http://www.answers.com/topic/focalization-2#ixzz1OI5nc4Dx
(7)Bal, Mieke ([1985] 1997). Narratology: Introduction to the Theory of Narrative. Toronto: U of Toronto P.

(8)http://hup.sub.uni-hamburg.de/lhn/index.php/Focalization