Light a White Background Black

Posted on: October 19th, 2011 2

The Concept

Click for larger image

For those of you who are considering investing in a bunch of seamless backgrounds…..say white, black, various colors……in a word, “don’t”. Get white…..just white. You can use a white background in any way you want, in any color you want, all without resorting to Photoshop. How? Well, you need lights; either studio strobes or some speedlights, some color gels, and a decently-sized room. If you are so equipped, then a white seamless background is all you’ll need!

The idea is really simple. You light your subject completely independent of the background. If your subject is far enough from said background, any light-spill will not impact on the background at all. In this way, you can set up 2 separate light zones; one for the subject and one for the background.

Light the Subject

I decided to shoot a vocal mic. Don’t ask me why…I have no idea. At any rate, I wanted the background dark with sort of a red halo behind the mic. The lead photo is the result. Here is the setup:

Obviously the seamless is white. The subjcet, the mic, is about 6 feet in front of the seamless, and being lit with a strobe from camera left. The light is directed with a 7′ reflector, into which a 20º honeycomb grid has been inserted. This pretty-much guarantees that the light will have a narrow beam with little to no side-spill. It so happens this light was set at f/22; pretty strong since my camera was set at f/11. To the right of the mic is a 12″ silver reflector, which bounces enough light back onto the right side of the mic, creating a nice 3-dimensional quality.

Light the Background

At 1/125th, f/11 and ISO 100, I have effectively cancelled all ambient light in the shot. That of course means the entire scene is lit by the 2 Einstein strobes. As you can see from the above setup shot, the second Einstein is about 3 feet off the ground and about 2 feet from the seamless. Additionally, I have a 7″ reflector with a 10º grid and a red gel in front. This throws a very directed circle of red-tinted light onto the seamless. At this point, all I had to do was aim it so the the circle of light lined up with the mic, which as you’ll recall was 6 feet from the seamless. Taking a test shot took care of that.

I find that many novice photographers completely over-look the importance of focal length when composing their shots. It turns out that the focal-length you shoot at has a dramatic effect on the look of your composition. I shot this with a long lens at 180mm. That compressed the scene front-to-back, so the seamless appears to be much closer to the mic than it actually was. If I shoot it at 50mm, I’ll need get much closer to the mic, but the circle of light thrown onto the seamless will be smaller. Compare the 2 photos:

Shot at 50mm

Shot at 180mm

That’s a pretty dramatic difference, right? I know that when you are learning, you pretty-much have your hands full trying to wrap your brain around the bass-ackwards f/stop numbers, the bizarre shutter speeds displayed between 1/4″ and 1″, the exposure triangle, etc. There’s a lot to learn. That’s why focal length gets over-looked. I’m here to tell you that focal length is a very powerful creative tool that is easy to understand and fun to use!!! Just remember that long focal lengths compress front-to-back and short focal lengths expand front-to-back. Let’s get real arbitrary and say long is 100mm and above, and short is 35mm and below. Let’s call anything in between “mid-range” and say that these focal lengths minimally distort front-to-back. Let’s avoid the discussion about camera position, focal plain, and depth of field. Let’s further avoid the entire discussion about Crop Factor for now. You have enough on your plate if you are just starting out.

The good news is that focal length operates completely independently of exposure, so even if you dial in the green-square “weenie mode” (AUTO) on your mode dial, you can still play with your focal length to get different looks! The bad news is that you will probably need to purchase at least one other lens, unless you have one of the newer “do-it-all” lenses from Nikon or Canon that have focal lengths of 18-200mm.

In Conclusion

The thing you should be aware of when getting the proper light ratios is that any time you put any sort of modifier onto a light, you are probably decreasing it’s output. The red gel, for example, caused me to loose 3 STOPS of output! The point is, don’t waste time setting up lights and measuring output until you have your light modifiers in place. Er, I did just that, so I know. Also, as per above, be aware of the different looks you get at different focal lengths. Always, always, always FOCUS! You can’t ruin a photo any faster by not properly focusing, and by focus I mean setting your focal plain in the proper position so your depth of field will cover our subject.

Speaking of depth of field, at some point you are going to need to come to grips with the relationship between focal length and depth of field. Contrary to what you may have been taught, the distance from your lens to the focal plain has much more influence on DoF than your f-stop. Happily, I will do a blog post on this very topic in the near future.

2 Responses

  1. Jeff W says:

    Gary,

    GREAT article and so easy to understand. I just signed up for your Newlsetter. I am curious, I shoot Canon and use the 430EXII Flashes– Any particular gels you recommend?

    Thanks Jeff

    • Gary Dates says:

      Jeff,

      this one’s easy. Just get the Rosco Strobist 55-Piece Filter Kit! It is only $7.95 and gives you color-correcting as well as special FX color gels (used in article). They are the perfect size for a speedlight. I must warn you though, you’ll have a hard time changing the color of a seamless backdrop because the coverage/output of a speedlight is limited compared to that of a studio strobe. Regardless, the best way to learn is by doing, so have at it!

      Best, Gary

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