Lighting for a large white background.

[gsxturbo]

Hello,

I'm going to be doing a very large group in the next few months and I want to make sure I have the right lighting.

The back wall will have 10' high by 20' long seamless paper and the floor will have 20' long by 20" deep of seamless white paper.

I have 2 white lightning 1800's I'll use for the front lighting and I'm wondering what I should use for the back lighting. I'd like to stay in the white lightning family so I was thinking maybe a couple 800's with barn doors or will that not give me an even amount of light. I've seen some large group white background pictures online where the photographer hasn't set the background lighting up right so you get very splotchy bright white in some areas and grayer areas in another.

Any feedback would be great! Thanks!

 

[Derrel]

I would use two identical lights on the background, aimed in from NOT TOO CLOSE!!!! Use larger parabolic reflectors; 65 degree beam spread reflectors work fabulous for lighting large expanses of wall or paper. using two-way barn doors on each light keeps stray light from hitting the people in the group.

I say do not put the lights "too close" because as you know, the closer a light is, the more-rapidly it falls off in intensity! if the light is pulled AWAY from the target area a bit, then the loss of light becomes almost imperceptible. I would say the right angle is about 60 degrees on a really wide background, a bit closer to 45 degrees on a standard 9 foot wide seamless, to cover the background evenly. In the center of the background area, where the light has traveled the farthest from the light source, since you have two lights, you can allow a small amount of overlap from each light, to keep the center even in intensity. Again, the key in to make sure the background light is even across the width of the backdrop.

I'd say put the lights from about 1/3 to as far as 1/2 of the way in front of the way from the wall toward the camera, and have 66% to 50% of the subject area in front of the paper. If you want to, you can set up large flags, to keep the background lights from hitting the people AND also to keep the lens from flaring on any glancing light, which can be a problem in a dark studio. Again if you have a really BIG background to light, evenly, you want the light sources to be NOT CLOSE, but instead to be "pulled back a ways", which is counterintuitive to many people who do not fully understand the nuances of the Inverse Square Law.

If I am reading this right, the background is 20 feet wide; so that means each background light needs to cover about a 10 foot wide swath. If you do not have any 65 degree metal reflectors, you could also use two umbrellas; reflecting umbrellas, or enclosed umbrella box modifiers are decent choices.