Skip to content

6 min read

How to light a green screen on a budget

A clean key comes from three things, and only one of them costs money: an evenly lit screen, distance between the subject and the screen, and a subject lit to match the background they are going into. With four lights, or three and a window you can black out, you can do all three in a spare room.

Two jobs that must not touch

Think of it as two separate setups sharing a room. The screen gets its own light, whose only job is to make the green flat and even. The subject gets their own light, whose job is to look like the shot they will be composited into. Every problem on a budget green screen comes from one of those setups leaking into the other: the screen light spilling green onto a shoulder, or the key throwing the subject’s shadow onto the screen.

The kit, at its smallest

  • Two soft lights for the screen. LED panels, or anything with a softbox, as long as the pair match in colour temperature and output.
  • One soft key for the subject. A light through a softbox or bounced into a white board.
  • One small hard light for the rim. The cheapest light in the kit and the one that does the most for the key.
  • The screen itself, pulled tight. A cheap fabric screen stretched on a frame keys better than an expensive one hanging in folds.

Light the screen first

  1. Remove the wrinkles. Stretch the fabric, clamp it, steam it if you can. Every fold is a shadow, and every shadow is a darker green the keyer has to guess about.
  2. Put one light either side of the screen, at the same distance and height, angled across it at roughly 45 degrees so each one covers the far half.
  3. Check it evenly, with a waveform or false colour if your camera has one. The screen should read as a thin, flat band. A hot spot in the middle means the lights are too close or too direct; move them back or add diffusion.
  4. Expose the green for a solid mid-tone, not bright. An overexposed screen goes pale and spills more; a dark one gets noisy. Aim for even first, level second.

Then move the subject away from it

Distance is the free part. Green light bouncing off the screen lands on the subject’s back, hair and shoulders, and it falls off fast as they move away. Two to three metres from the screen is a good target; in a small room, take whatever you can get. Distance also stops the key light casting the subject’s shadow onto the screen, which is the second most common reason a budget key fails.

If the room is too shallow to separate them, frame tighter. A medium close-up needs far less screen behind it than a full shot, and the screen lights can sit closer to the fabric without being in frame.

Light the subject like the plate

Decide the background before the shoot. If the plate is an office with a window on the left, the key goes on the left. If it is a sunset, the rim is warm. A subject lit flat and front-on looks cut out whatever the keyer does, because the light on them disagrees with the light in the picture.

The rim light, from behind and to one side, draws a clean edge around hair and shoulders and overpowers any green that is left on them. It is what makes the matte hold at the edges, where cheap keys fall apart.

Camera settings that help the key

  • Faster shutter for movement. Motion blur on hands and hair mixes subject and green into one smear. If the subject gestures a lot, a slightly faster shutter than usual keeps edges crisp.
  • Record the best codec you have. 10-bit and 4:2:2 colour hold far more edge detail than 8-bit 4:2:0. If the camera offers it, use it for this shoot.
  • Focus on the subject, not the screen. A soft screen is fine, even helpful: it hides the weave of the fabric.
  • Nothing green, nothing shiny. Check wardrobe, jewellery and glasses before anything else.

Draw it before you rig it

A green screen setup is a floor plan problem: how deep the room is decides how far the subject can stand from the screen, which decides how tight the shot has to be. Five minutes with a scale drawing saves an hour of moving stands. The green screen lighting diagram shows this setup to scale, and the free lighting diagram maker lets you draw your own room and move the lights until it fits.