Creating Realistic Moonlight is Complicated

Moonlight. Not the movie. I mean, light from the moon. Moonlight is something filmmakers have been lighting their scenes with forever. Except, moonlight in movies is never real. Light from the moon is not nearly bright enough to be visible to most cameras. So filmmakers make fake moonlight with big lights, and it's generally accepted as moonlight. If you've ever tried it yourself though, it's not that easy to get right. I've had a lot of struggles nailing that perfect moonlight look. Often, it just looks like there's a street light outside. I've wondered why it's so hard to get moonlight right. Turns out there's actually a lot of science that goes into why moonlight looks the way it does. And it's probably more complicated than you think. So come with me to learn how to make perfect moonlight. Let's start by saying there isn't any one right way. Every DP or gaffer will have their own moonlight recipe. And sometimes they'll just shoot it during the day and color grade it to look like night. So we'll be exploring a few different moonlight looks. Our first look is with soft moonlight. We're adding the shower curtain in front of our light to soften it. After all, moonlight is soft. Right? Wrong. Let's start by defining soft and hard light. This is soft light. You can tell by how diffused the egg's shadow is and by the slow fall off of light on this side of the egg. Don't ask me why I'm using an egg. Soft light is more flattering on faces and used very often in film. Right now, I'm being lit with soft light. You create soft light by making your light source larger, which by adding a shower curtain in front of our light, we're effectively making our light source the size of the shower curtain. Alternatively, this is hard light. Look at how crisp that shadow is. We're getting this because of how small our light source is now. This is the same quality of light as sunlight, since the sun is a small point of light in the sky. But you know what else is a small point of light in the sky? The moon. Now, we all know that the sun is larger than the moon. Much, much larger. Like 400 times larger. But wouldn't you know it, the sun is almost 400 times further away. 390 to be exact, making the two very comparably sized in the sky from our perspective on earth. Same light source size, same quality of light. So the moon is actually hard light, just like the sun. You can even see if we brightened our light up a little bit and warmed it up in post, this looks more like sunlight. Not quite, for reasons I'll get to in another video. So that's it. No, not even close. Speaking of close, the closer a light is to an object, the more light that object blocks, creating a larger shadow. As we move the box away from the light, the shadow becomes smaller. You can tell by the angle of the shadow and how the edges of the shadow become more parallel. Invert this for a window. Now the area the light hits creates our angle. We can especially see what's happening when we bring down the blinds. See how the shadows of the blinds sort of fan out? Because the sun and the moon are so far away, they create something called directional light. They create perfectly parallel shadows. So the further from the window we bring our light, the more directional the light will be, and the more parallel our shadows. This is why we're getting something that looks more like there's a street light outside rather than the moon. Even if you didn't know about directional light, we can still all intuitively pick up on the difference. But wait. With this shot, how can we tell how directional the light is without the light hitting the wall or anything other than the floor? With haze. Haze is basically just a bunch of tiny particles. Light bounces off those particles which illuminates its path. Essentially, we're recreating what we saw on the wall just in the air. And now we can see just how non-directional our light really is. What we should be seeing is far more of these beams of light heading in the same direction. So we'll need to bring our light further away. But when you move your light back like this, you lose a lot of brightness. So we're gonna use a fresnel to brighten it up. And now we have our second moonlight look. Uh, but not quite actually. Believe it or not, we're still not done. When bringing your light so far away, you can't get it very high in relation to the window. This is important because the moon is often quite high in the sky. So we need a taller stand. Or we can use science. Mirrors reflect light. Meaning they continue the path of light in a new direction. So add together the distance from the light to the mirror, and from the mirror to the light's final destination, and now you have the total distance from the light to whatever the light is hitting. In this case, it's almost like the flashlight is somewhere off screen. So our light can travel the same distance in half the space, allowing us to get our mirror closer to the window, and thus allowing us to get a higher angle of light on the window. In hindsight, we didn't do a great job of this, and should have gotten our mirror a bit higher and a little closer, but the concept still applies. Finally, for real this time, we have our second moonlight look. However, we're still not quite to perfect moonlight yet. There's still the question of color. Everyone knows that moonlight is a pale bluish color. Except it's not. We see moonlight as blue due to the Purkinje effect. As your eyes become accustomed to lower light levels, they're slowly shifting from full color vision using cone cells to light-based vision using rod cells. Your eyes stop shifting somewhere in the middle. This is called mesopic vision. Rods alone don't pick up color, meaning by themselves, you'd see in black and white. But because the cones are still partially active and the rods are most sensitive to blue-green light, you end up seeing moonlight as blue-green. In fact, the moon's color is actually about 4100 Kelvin, which is a warmer color temperature than the sun. Take a picture of the moon and you'll see just how warm it really is, because your camera doesn't operate on rods and cones. And that's the crux of the problem. Cameras don't operate like our eyes do, so we have to manually change our light to the proper blue-green. So just add a blue gel to the mirror and we're done. But of course, it's not that simple. It's not enough to simply have blue light. We need to eliminate all color that isn't blue-green. You may have noticed the red flowers next to me. I also happen to have a red shirt on. Due to the Purkinje effect, our eyes now see blue-green as bright, making other colors darken towards the ends of the visible light spectrum. So reds need to lose their color and darken. We can do this with color grading. In fact, quite effectively with just plain white light. So why bother with the blue gel in the first place if we can just color grade the image to be blue? See, adding gels to lights doesn't really matter when it comes to a monochromatic image. Monochromatic meaning an image of all one color. We can manipulate the image to be any one color with ease regardless of where it started. It's when you have an image with multiple colors and you want to keep them. That's when gels come in. Realistically, you wouldn't see moonlight with lamps on like this. This is where we take an artistic approach. One that's taken in many movies. If we color grade this shot the same as we did before, our lamplight becomes blue just like the rest of the scene. So this time let's use a set of gels with a less intense look and will also help darken the reds. Roscoe sent me out their white flame green gel to try this and when paired with a full CTB gel, which stands for color temperature blue, we get this. The reds are still visible and there's nothing we can really do about that, but they are darker comparatively. See how my red shirt is more red in the background than in the moonlight? But the monochromatic image is really where the moonlight shines. This is accurate moonlight. This was my first time making moonlight like this, but I think I've found my new moonlight recipe. At least for now.