The Key Light effect draws a soft-edged wash of light across your screen that's bright at one corner and fades to nothing diagonally across it, so the screen becomes a directional light source rather than a flat one. That's what gives a subject visible shape and shadow instead of the flat look of even, all-around lighting.
Before you start
- A screen you can angle toward your subject. A monitor, laptop, or tablet all work, but the effect needs to be able to face your subject from one side, not head-on.
- A camera and call or recording app running on a separate device or window, so you can watch the effect land on your face while you adjust it.
- A second light source, if you can arrange one, to act as fill. A key light on its own is meant to leave one side of the face dimmer — that's normal, not a fault — but a fill source (a room lamp or a second WebLight screen on Fill Light) lets you control how deep that shadow gets.
Set it up
- Open the Key Light effect on the screen you want to use as your light.
- Position that screen off to one side of your camera, roughly 30–45 degrees from center, angled toward your face. Keep it slightly above eye level, tilted down.
- Set Color Temperature to match your room lighting — Daylight near a window, Tungsten or Warm White under household bulbs.
- Set Brightness to 80–100 to start. Key light is meant to be the strongest source in the shot.
- Select Go Fullscreen so the whole screen becomes the light. The controls fade out after five seconds without mouse movement.
- Check your camera preview. You're looking for a bright side and a shadowed side with a visible transition across your face, not an even wash.
You'll know it worked when one side of your face is clearly brighter than the other, with a soft gradient between them rather than a hard split.
To leave fullscreen, press Escape or move your mouse and select Exit Fullscreen.
What each control does
| Control | Range | What it changes |
|---|---|---|
| Brightness | 10–100 | Overall strength of the light. Key light usually wants to run brighter than fill or ambient sources — start high and pull back if it clips. |
| Color Temperature | Daylight, Cool White, Neutral, Warm White, Tungsten | The color of the light, from 6500K neutral daylight down to 2700K warm. Match this to your room lighting so your camera's white balance doesn't fight it. |
Key Light has no other on-screen sliders — no size, position, or angle control. Direction and reach come entirely from how you physically place and tilt the screen, which is the main thing to get right with this effect.
Common setups
- Interview or talking-head video. Screen at 40–45 degrees, Brightness 85, Daylight or Neutral. Gives a clear, professional-looking side of definition without going dramatic.
- Moody podcast or narrative look. Screen closer to 60–70 degrees from center, lower in the frame, Brightness 90–100, Tungsten or Warm White. The steeper angle and warmer tone push more of the face into shadow for a more cinematic feel.
- Key plus fill on two screens. Key Light screen at 30–45 degrees at Brightness 85–100, and a second screen running Fill Light on the opposite side at Brightness 40–50. The fill screen lifts the shadow side without erasing it.
- Product or object demo. Screen close to the subject, angled from above at roughly 45 degrees, Brightness 70–80, Cool White. Keeps texture and edges visible without blowing out highlights.
Troubleshooting
There's a hard, harsh line across my face instead of a gradient. You're too close to the screen, which compresses the fade zone. Move back a foot or two so the gradient has more physical distance to spread across before it hits you.
My glasses are throwing a bright glare. The bright corner of the gradient is hitting the lens straight on. Tilt the screen down a few degrees, or shift your seating position slightly off the direct angle to the screen until the glare clears the lens.
One side of my face is almost completely dark. This is the expected trade-off of a single key light — it's directional by design. If it's too extreme, move the screen a bit more toward center to narrow the angle, lower Brightness slightly, or add a Fill Light on a second screen on the shadow side.
The light looks like the wrong color on camera. Your camera is white-balancing against the room, not the screen. Set Color Temperature to match your room lighting, then lock white balance in your video app if it offers that option.
The gradient doesn't reach far enough — most of the screen looks dark. That's how the effect is built: it fades to transparent well before the far edge. Move the screen closer, or shift your sitting position toward the bright corner instead of expecting the light to fill the whole frame.
The screen is blank and no key light appears. Graphics acceleration is most likely switched off in your browser. Turn it on in your browser's settings and reload. If that isn't an option, Full Screen Light is a simpler effect that doesn't need it.
Next steps
Pair this with Fill Light on a second screen to soften the shadow side, or use Ring Light instead when you want even, shadowless coverage rather than directional shape.