Background problems

[filter99]

I am still teaching myself a little in the studio department but when i use a white background it all looks ok in camera and in lightroom but when i print or load the pics up to facebook it stops being white! Why is this?
I am using two 300W lights with softboxes at 45degrees either side of the subject

 

[Garry Edwards]

I am using two 300W lights with softboxes at 45degrees either side of the subject

Which subject is this - front or rear?
You need to be aware that there are 2 subjects, the person or whatever that you're photographing is the front subject and the background is the rear subject, and if you want the background to look white then you need to light it - in fact there needs to be slightly more light on the background than on the front subject.

Lighting that goes past the front subject to the rear subject won't do it, the light has to travel further and so has less power by the time it reaches the rear subject. For example, if the light has to travel twice as far to the rear subject as it does to the front subject then only about a 1/4 of the light will reach the rear subject.

 

[Clickawaymedia]

Yeah, as Garry said, the background and the subject need to be treated as 2 seperate objects, and need to be lit seperately.

I would try to use 3 lights if you have access to an extra one. 2 to light the background, and 1 on the subject (with a reflector if needed to lift shadow). dont use softboxes on the background lights. Use background reflectors if you have them, if not then the normal spill-kills would do. The backround probably needs to be +2 stops lighter than the subject.

 

[vaizki]

And try to leave ample room between subject and background as well. That will lessen the effect of the background reflecting light that will burn the edges of your subject to a white mush, especially hair. Been there...