Ill start with a brief look at the history of lighting, and then describe the optimal procedures for lighting for streaming, including a brief look at the requirements for shooting for chroma key. Along the way, Ill describe how to use the zebra stripes on your camcorder to determine when youve got sufficient lighting on the set.
In this article, you will learn:
- The difference between flat and three-point lighting, and when to use each technique
- The difference between hard and soft lighting, and when to use each
- How to use your camcorder and/or video editor to determine whether there is sufficient light on the set
- How to light for chroma key.
Use at Least Three Lights
Most lighting setups are variations on the same three-point lighting scheme; you change the effect by varying intensity, for example, to create shadows or flat lighting, and by using hard or soft lights. Three-point positioning is shown in Figure 1. On the left is the shot from above, showing the two front lights angled at about 45° in front of our subject, and the back light close to the subject and pointing down on her head and shoulders.
Figure 1 The basic three-point lighting set-up: two in front, one in the back.
On the right is the view from the front, showing all three lights positioned above the subject. The two front lights are pointing down at between 1525°. Since the back light is closer to the subject, its pointing down at a more severe angle, say 75°.
Obviously, the two front lights provide the main light for the scene and Ill spend lots of time on them below. The primary job of the back light, however, is to help contrast the subject from the background, which is demonstrated in Figure 2.
The image on the left has no backlighting, and you have a tough time distinguishing the subjects shoulders from the back wall. On the right, you see the lights reflecting off his leather jacket, which is subtle but creates the necessary contrast with the similarly colored back wall. Remember that compression reduces the detail and contrast in the image, which makes backlighting absolutely critical.
Figure 2 How backlighting (shown on the right) helps create contrast between the subject and back wall.
Not to preach, or beat a dead horse, but when shooting for streaming, dont ever ignore backlighting; its probably the most frequent error I see in streaming video. You can choose not to use backlighting in certain circumstances, but always consider its use. Note that back lights are also called rim lights or kickers.
Keep the following thoughts in mind when selecting and setting up your back light:
- I typically use a hard light for backlighting (described below).
- The light intensity should be between 50100% of the intensity of the stronger of the two front lights, and I typically use 50%. If youre using 1000-watt fixtures in front, for example, try 500 watts.
- When setting up the back light, make sure that it doesnt shine into the camera or create a light halo.
- Also, be sure that the back light is positioned far enough to the back that it doesnt shine on the subjects forehead.
Use Soft Lights
There are two types of light sources, hard and soft lights. Hard lights are generated by relatively small sources of lights that transmit directly to the subject, and include incandescent and halogen bulbs, and the sun (I know its pretty big, but it is really far away). Hard lights create a very distinct, well-defined shadow, like that on the left in Figure 3.
Figure 3 Hard lights on the left, soft lights on the right.
The problem with hard lights in the streaming scenario is that they create significant contrast between the lighter and darker regions in the image (like the right and left side of my face) and lots of lines and other detail, which combine to make it tougher for the codec to do its job. Hard lights are also tougher on the subject of the video, and can create that deer in the headlights look, and also are generally hotter.
Soft lights are more diffused, and light the scene without creating the same problems. You can buy or create soft lights in many ways, including:
- Buying fluorescent light fixtures, originally offered by Kino Flo incorporated, and now offered by most lighting vendors, including Lowels excellent Caselite models. Fluorescent lights have the benefit of being much cooler than incandescent or halogen bulbs, but require a much greater area to create the same light intensity.
- You can soften hard lights by installing a soft box around the light, reflecting it off an umbrella or reflector, or even a white wall or piece of foam board. Ive used Lowels Rifa-Lite soft box with very good effect as described below.
- You can also soften hard lights by placing a scrim, gel or other diffusion material over the light source.
Have another look at Figure 3, and note that the left side of my face is darker than the right in both images; the distinction is just starker with hard lighting (on the left). This is the shadowed look Ill cover in the next section, which helps create depth and contouring in the face. For now, understand that you can use soft lights to create both shadowed and flat lighting, though most producers seeking flat lighting will use soft lights.
Overall, I recommend using soft lights over hard when shooting for streaming. As youll see in the next section, I also recommend flat over shadowed lighting. I just wanted to be clear that theyre not the same thing.
Use Flat Rather than Three-Point Lighting
Compare the lighting in Figure 2 and Figure 3. In the first figure, both sides of the face are lit evenly; in Figure 3, shadows are evident on the left side of my face. These are the two techniques discussed in this section. Note that while both flat and shadowed lighting use three lights, lighting designed to create shadows is typically called three-point lighting, while lighting designed to avoid shadows is called flat lighting.
Note that three-point lighting originated as a way to create contrast on grainy black-andwhite film and later black-and-white television. Shadows also help create mood, as in film noir pictures with detectives in fedoras with half-lit faces.
Its a killer look for film, but most streaming producers avoid it, as do most news, sports and entertainment producers on TV. Why? In the streaming environment, the shadows and contrast created by three-point lighting are very hard to compress at good quality, especially at low bit rates.
On TV news shows, anchors tend to move too much to sustain three-point lighting, which is challenging to maintain when the subject is turning around or standing up and sitting down. Its very challenging to produce three-point lighting when you have multiple subjects on the set, especially if theyre located close together.
Also, three-point lighting requires intense hard lights like incandescent, which are harsh on the eyes and hot. For these reasons, most studios have switched to banks of softer fluorescent lights that light both sides of the face equally, producing overall flat lighting. In fact, in my survey of 13 news-oriented shows that post streaming video to the web, including CNN, CBS, ABC and ESPN, none used three-point lighting. Instead, all moved to entirely flat lighting.
One key reason almost certainly relates back to one of the original purposes of threepoint lighting, to create mood. Unless your workplace is a lot more exciting than mine, creating mood probably isnt a goal in your streaming video, particularly for the Q3 earnings announcement or description of a new product offering.
Now there are some exceptions, most notably a series of streaming testimonials offered by Hewlett Packard you can see here.
Check out the Digital Entertainment + HP video, in particular. However, theyre all extraordinary from a streaming video perspective: 480°360 video at less than 300 kbps ( Windows Media, not Flash) with excellent quality and interesting use of three-point lighting. Still, theyre product testimonials, so mood lighting is appropriate, and its mostly used in oneperson interviews where conditions can be tightly controlled.
Other factors in the video quality include the large resolution, which provides the pixels necessary to display the contrast created by the shadows; at 240°180 resolution or below, these would look pretty silly. These videos also have a done by professionals, dont try this at home feel, and look like they were shot by professional HD camcorders. OK, Im done drooling.
Overall, if you have video that would benefit from the shadows produced by three-point lighting, go for it, but keep in mind that flat lighting is much easier to produce and harder to mess up. For all other videos, I recommend using flat lighting.
Creating Shadows with Three-Point Lighting
The set-up for three-point lighting is shown in Figure 4. Generally, when your goal is to create distinct shadows, your three-point lighting set has three types of lights: key, fill and back.
Figure 4 Lighting set-up for three-point lighting.
The key light is the strongest light, and generally should be a hard light, to ensure noticeable shadows, or a soft light placed close to the subject. When placing the key light, keep the following considerations in mind:
- Mind the nose caret, or the shadow made by the nose. Dont cross the nasolabial fold, or the crease that runs from your nose to mouth. In Figure 5, the image on the left is almost directly in front of me, so the shadow is limited to the extreme left side of my face. Moving the light over to about 45° produced the image in the middle, where the nose caret is almost perfectly placed in the fold. On the extreme right, the lighting is too far to my right, and the nose caret extends beyond the fold.
- Also, adjust the height of the light so that the nose caret doesnt cross the lips. Note that the subject is going to move, so you want to find a good middle positioning within that range of motion.
Figure 5 Dont cross the nasolabial fold.
The goal of the fill light is to soften the harsh shadows produced by the key light, particularly if the key is a hard light. Its positioned opposite the key light and is generally a soft light with about 50% of the power of the key light. If you have two lights of identical power, move the fill light back to weaken the light.
Again, the goal of the back light is to create contrast with the background and it is generally a hard light shined down on the subject at about 75°, at between 50100% of the key light.
Creating Flat Lighting
There are multiple ways to create flat lighting. For example, many studios use banks of fluorescent lights to light all newscasters on the set equally and evenly.
Using a traditional three-point lighting system, you have two basic alternatives. The first is to use two key lights, as shown in Figure 6, along with the back light, of course. The second is to use a single soft light, positioned directly above the camera. In a recent shoot, I tried both approaches.
Figure 6 Creating flat lighting with two key lights.
Briefly, I was using a Lowel DV Creator 44 kit for the shoot, which includes four different lights. In the dual key setup, I used an Omni-light and Rifa-lite as my two keys. I used a 500-watt bulb in the Omni-light, faced it away from the subject and attached the umbrella to shine the soft light back at the subject. On the other side I used the Rifa-light soft box with a 250-watt lamp positioned much closer to the subject.
This is a fairly common scenario for producers who have traditionally used three-point lighting. Since you dont have two lights of equal power, you simply have to move the lights further or closer to the subject until their face is shadow free.
In the single key light setup, I used the Omni-light and umbrella directly behind the subject, positioned about 25° above the camera. I used a 150-watt clamp light as the back light for both shots, and shot both videos with a Canon XH A1 HDV camcorder in manual mode, with a shutter speed of 60, gain disabled and aperture adjusted as described below to eliminate the zebra pattern.
The results are shown in Figure 7, with the dual-key video on the left and single-key on the right.
The dual-key approach produced slightly more light to the sides of the face, and a bit less shadow under the chin, and is a touch darker, though I could have fixed that at the shoot by coming down one more f-stop. Overall, the images are very close; if you didnt know what to look for, you probably couldnt tell them apart.
Figure 7 Flat light produced by dual keys on the left and single key behind the camera on the right.
During the shoot, the subject noted that the single key was a bit harder on the eyes, but bearable so long as he looked into the camera and not the lights. It did produce a glare over his right shoulder, which would have darkened the face had I been shooting in automatic mode.
On the other hand, the single-key shot is shadow free, eliminating shadows seen in the dual-key approach on the bookshelf and the small shadows from his collar under the neck. While shadows werent a problem in this shoot, the single-key approach would be much, much simpler in situations where shadows are an issue, particularly when shooting for green screen in close quarters.
Overall, I like the dual-key lighting a bit better, but the single-key approach is worth a try when you only have one key light or when shadows are a problem. I will definitely try it on my next green-screen shoot.
Miscellaneous Deep Thoughts about Lighting
The writer in me just cant let gothere are some additional points that scream to be told. So here they are:
- Watch lighting on TV. Im not saying that TV styles should dictate your work, but paying attention to lighting between the scores and news can illustrate the art of the possible. Once I noticed that lighting used by ESPN eliminated shadows under the nose and chin, I immediately dropped the height of my lights.
- Mind your color temperatures. This is a chapter all to itself, but the bottom line is: dont mix incandescent (which are yellowish in tint) and fluorescent lights (which are generally bluish). Or sunlight and either of them. Your camera wont know which color to white balance to, and white will appear off tint in one section of the image or the other.
- You cant spend enough time setting up lighting. Usually, youll know if audio is working or not within minutes, but lighting takes a lot longer to get right. So budget your time accordingly.
This article includes text and images excerpted from "Hands-On Guide to Flash Video,". Copyright © 2007. Reprinted with permission from Focal Press.
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