lighting a background from front or back

[yoshi]

Hi,
Trying to find any information on this is proving difficult.

Are there various situations in which you would light you backdrop from behind rather than from the front?

Assuming your backdrop is a white bed sheet or cloth backdrop.

I am thinking you should light from the front to cut down on light spill and or flare.

Am I thinking along the right lines or am I way off?

May seem a silly question but for some reason it's bugging me

 

[Garry Edwards]

The only good reason for lighting a background from behind is to save space. That's why the Lastolite Hi-Lite is so popular, and why most of us used large softboxes as backgrounds from time to time before the Hi-Lite became available.

Flare is one of the problems, because a backlit background will always cause lens flare (yes, of course I know that some lenses are better than others but all that means is that the flare is less obvious with some lenses than with others)

Light spill, or wrap, is a product of size and distance and occurs regardless of the direction the light is coming from.

Edge degradation is the biggest simple problem with any overlit white background and is worse with backlit ones.

 

[lawrie29]

I have found that lighting from behind needs lots of power unless you are using a very thin material, a bedsheet is too thick in my experience.