How to Light Rain, Smoke, or Fog for Film

It seems so easy, doesn't it? You've set up the romantic climax of your film, where the two lovers reunite in the rain, or the creepy sequence where the killer emerges out of the fog. The rain begins,
or you turn your fog machine on, and you're off and rolling. But you get the film back and there's no rain to be seen, just two wet actors; or the fog looks like little more than a light mist or heavy breathing on a cold day. What happened? As it turns out, there's a right way to shoot rain, snow, fog, smoke and even misty breath on a cold day. It's called backlighting.

Difficulty: Moderate

Instructions

Things You'll Need:

• 100W-15,000W light(s), depending on how much light you'll need (one actor? or a charging horde of extras?)
• Barn doors and stands for the lights

1. With any complicated film setup, it helps if you can rehearse the rain or smoke effects, instead of standing around, ready to roll when the downpour begins or a real fog rolls in. However, if you don't have a rain machine, or are trying to conserve those fake snowflakes or
   smoke cookie for when you absolutely need them, you can pre-light the scene even without testing it and expect a reasonably good result. First, set up your scene as you want it to look, with your key, bounce and fill lighting. Don't set your rim lighting or backlighting yet,
   as these will be effected by your smoke or rain lighting.

2. Set up anywhere from one to four separate, additional, ambient backlights, either high above the actors as ambient light, or low near the ground as practical light. The lights should all be in the background, with the actors between the lights and the camera.

3. Aim the lights in the direction of the camera, anywhere from 45 degrees to nearly straight on, so the light falls through the rain or smoke to the camera lens. The higher the light, the better to avoid lens flare, unless you're imitating headlights or other practical lights in the background. If the light is supposed to be atmospheric, diffuse it as much as you can afford to get maximum coverage of the rain and snow and minimal disruption of the lighting on the actors. A hard pool of backlight will light your rain or fog just as well, however, if you really want that "noir" look.

4. Set your rim and backlights for your actors, taking into account any additional light falling from your additional backlighting. Or, simply use your rain or fog lights as the backlighting for your actors.

Tips & Warnings

• The more rain, snow or fog you have, the better. Obviously the script determines how much you want to see, whether it's a light fog or a whiteout, a drizzle or a downpour, but better to err on the side of too much than have nothing appear.
• Rain will brighten your backlight, so be sure to view the rain through the lens before you shoot, in the event you need to dim your light a little after the rain begins to fall.
• The rain, fog or snow closest to the light source will appear brightest, which can create a great effect or an unwanted one, so be aware.
• Elements like rain and snow will show up best against a dark background--like trees, buildings, or even a night sky. A grey or white overcast sky can render all your work invisible.
• A quick note: these steps work just as well for smoke, snow, sleet, rain or fog, so we'll see these options used somewhat interchangeably throughout the article. The same steps apply for all.
• If you are shooting in real rain, make sure your lights are properly covered or protected! Cold rain can shatter a hot bulb on contact.