user11714: I got this from les mesirables (2012) movie. in this scene, guy singing, but camera blur all his around, focusing only on him. 
so What is this name of the video effect?  

user4426: Mulvya is right - it's shallow depth of field, achieved by having a lens with a wide open aperture, corresponding to a low F stop number.

user1871: Shallow depth of field or focus.

11714: <p>I got this from les mesirables (2012) movie. in this scene, guy singing, but camera blur all his around, focusing only on him. <a href="https://i.stack.imgur.com/40Oh9.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/40Oh9.jpg" alt="enter image description here"></a></p>

<p>so What is this name of the video effect?  </p>
 4426: <p>Mulvya is right - it's shallow depth of field, achieved by having a lens with a wide open <a href="https://en.wikipedia.org/wiki/Aperture" rel="nofollow">aperture</a>, corresponding to a low <a href="https://en.wikipedia.org/wiki/F-number" rel="nofollow">F stop number</a>.</p>
 1871: <p>Shallow <a href="https://en.wikipedia.org/wiki/Shallow_focus" rel="nofollow">depth of field</a> or focus.</p>
