Gradient White Background

I would use cyc lights and allow a natural fall off (gradient) by feathering the angle of the lights.

The DOF is helping the gradient smooth out.

The waveform monitor will be useful to show you that you have a gradient (fall off)

It will become thicker on the horizontal axis
 
I have found both in photography and video that if the background curves near the bottom to horizontal on the floor and it lit straight on, that there is less illumination as it curves from vertical to horizontal. This gives the gentle gradient in the example video you showed. The trick is to have the lights not too far from the backdrop, if they are back where the camera is located, it will illuminate more evenly, but as you move the lights closer (one on each side) you will see more of a gradient. Also, you can adjust the curve of the backdrop to tune this effect. If you overexpose and "blow out" the backdrop completely, then the gradient is lost.
 
Back
Top