Day for night for color cinematography is an old shooting methodology that relies on a number of techniques regarding human perception, socially accepted convention, and technical qualities of film/sensors. There are a variety of reasons for shooting day for night, and understanding the whys and wherefores can help you create believable images.
Moonlight Is Blue
It isn’t really, any more than sunlight is blue. The reality is that moonlight is reflected sunlight, so why do people think moonlight is blue? Sunlight has a color temperature of roughly 5600K, which humans perceive as blueish when compared to light with a lower color temperature—like when you come in from outside and your apartment is dim and orange (those who grew up when most household lighting was tungsten may understand this better). For a more detailed explanation, check out Todd Vorenkamp’s excellent article Understanding White Balance and Color Temperature in Digital Images.
So, moonlight is just dim reflected daylight, and when you see it surrounded by campfires (which have a warm color temperature), your mind balances out the moonlight to blue, because the mind tends to take the brightest thing in your visual field (the brightest parts of the flame) and makes it seem white, shifting the color temperature of everything you see.
In an empty field not surrounded by lights, moonlight will appear gray because, at low light levels, the color receptors in your eye don’t work as well as the luminance receptors, so everything tends to look desaturated.
Psychologically we expect moonlight to be blue, and when filmmakers want to show a night interior, they will often fake moonlight coming in a window using a blue-hued light. Think about it: How many different moonlight blue gels are out there, and yet there is no moonlight orange?
If you watch old films from the 1950s, you will see a lot of day for night, where the production was shot with tungsten-balanced film during the day, leaving off the orange color correction filter (Wratten 85), and then not using fill as they normally would for shooting exteriors in the day. Watching the actors with their faces in dark shadows, while the sky and background behind them are bright, the scene has an overall blue cast that definitely doesn’t look like day.
Why and Wherefore
Back in the day, it made sense to shoot day for night, since film stocks were extremely slow and shooting at night, with all the light needed to get an exposure, required a lot of equipment, and that meant more time, more money, fewer shots, and a longer schedule.
What Does Night Look Like?
It is a fair question to ask, especially if you are going to try faking night. Of course, what night looks like would depend on where and when you are. Out in a cornfield in some small town in Kansas in the 1950s will look different from a modern-day metropolis like Hong Kong or Times Square. Still, there are things to note.
1. The sky is going to be dark—so for convincing day for night, avoid showing the sky. If you are just shooting a background plate, then perhaps you can get away with a polarizer and heavy graduated ND on the lens, but if you are shooting a scene with people outside—this is going to be very difficult. I would reference a “Midsummer Night’s Sex Comedy,” by Woody Allen. In fact, let me point out that Gordon Willis, the cinematographer, pulled off very convincing day for night by shooting those scenes in a grove of trees. Only very rarely could you see the sky peeking through the branches to spoil the effect.
2. There is a lot of light pollution during the day and, to me, night is cleaner, since the ambient light levels are so low. On the rare occasions I have had to fake day when shooting at night (night for day) I find it best to try to spill as much light as possible, even trying to introduce a small amount of glare. Something like an ARRI VariCon system or a low-level fog filter can help sell that. But when shooting day for night, keep the lens as clean as possible and the contrast up.
3. Shadows—one of the key ways to convey that it is night is with shadows. Shadows everywhere. So back or side-lighting your characters with the sun and closing down to prevent their hair from having that glamorous glow is a good place to start. Of course, you probably want to see the actors’ faces, so you will want to fill them. But here is where you can deviate from shooting for a daylight look by using less fill, or only filling part of the actors’ faces. It becomes a balancing act.
Day for Night Interiors
Shooting day for night indoors can be easier than shooting exteriors.
1. You can black out the windows that aren’t in the shot.
2. It is easier to control interior lighting, although it may limit using exterior lights shining through windows to create our friend “blue moonlight.”
3. For windows that are in the shot, you can black them out if the window shades are drawn—but if you are going to see through them, using ND gel on windows, or scrims, or even setting up black fabric (Duvetyne) far away from the window, can be effective. Tenting the window is also useful. Don’t use CTO if you want the outside to be slightly blue.
Shooting the Image Don’ts and Dos
Generally speaking, night is dark, and dim, which can raise issues, and also provides opportunities.
1. Don’t be afraid to have a dim image—yes, you are shooting during the day, but remember you are trying to sell it as night, so don’t be afraid of a dark image.
2. Be careful when closing down your iris. The more your iris is closed down, the more your depth of field increases, and it might be disconcerting to see a night scene with sharp backgrounds. Again, here is the perfect time for adding ND to your lens, to control the depth of field.
3. Avoid flashlights in the shot. Think about it: The flashlight is competing with the sun. It just isn’t going to work, and it won’t be believable.
4. Don’t blow out your backlight. Unless the actor is supposed to be standing in front of a raging inferno, don’t go for that glowing, blown-out hair light look.
5. Don’t show the sky.
6. Avoid anything white in the background, because it is just going to “pop” and ruin the effect.
1. Choose whether you are going for realistic-looking night, or a more stylized day for night effect.
2. White-balance your camera. Consider shooting with your camera’s white balance set to tungsten, or manually white-balance it to something between daylight and tungsten, just to get you started.
3. Break out your filters: ND filters, variable NDs, grads, polarizers, and even a few day for night options.
4. Along with the filters, break out the flags. It’s supposed to be night, so cut the sun.
5. Close-ups and medium shots will work better, mostly because you have a smaller frame to control; likewise, a longer lens that shows less of the background will help you out.
6. Be prepared for some post color-correction work, especially if you’ve gotten some sky in the shot to which you must attend.
A Final Thought
You may end up with no choice—due to budget, scheduling, location conflicts, or for other reasons—but to shoot some scenes during the day that need to look as if they were shot at night. If that happens, I wish you luck, and if you are making a stylistic choice, then more power to you, and push it as far as you dare. In either case, I hope this article has helped you be better prepared.
If you have any questions or have pulled off day for night (or tried and were not entirely successful), please feel free to leave any comments below—we always like to hear about different techniques.