lighting hairlight, backlight

[dvdguy]

hey guys,

I got another question about lighting and this time it covers the "hairlight". Its always been somewhat of a mystery to me.
I was wondering if the hairlight (or backlight) is used just to cover the contrast dilemma? I mean, some people have very dark hair and the light rays get absorbed by the color of the hair and results in no shine at all. So is that the main point? And the other reason of using is the separation of the subject from the background?. Basically these two things?

But from another view (personal view), wouldnt a a bright KEY for instance lit enough so that there wouldnt be no use for hairlight or backlight? Kinda like the sun, its so bright we notice that glow instantly. Wouldnt the walls behind you also "work" as the backlight or hairlight? Hell, even the ceiling for that matter

I dont know if you understand my thinking, its hard to explain..

Thanks

 

[PaulGriffith]

The main idea (like yous said) is to make the subject stand out from the background. Traditional video is very 2D and stuff starts to blend together real fast.

Not every shot will require a backlight. Sometimes you won't want it for artistic reasons.

A shallow DOF helps to create the same feel, separation from background. When you want the darker look or a "realistic" look in a scene that couldn't possibly have a backlight, a shallow DOF will do fine. Even that is an artistic choice.

Sometimes bouncing light off a wall can work for backlight, but if you are going for separation again that might not be the best approach. Usually light bounced off walls is more of a fill light.