This lighting technique is all types of good for low-budget filmmakers who don't have access to much lighting gear.
Are you a filmmaker with limited access to lighting gear? What about limited space to shoot? If you said yes to either (or both), the cross key lighting technique will become your life raft in the sea of aggravating and inescapable on-set challenges. In this video, Crimson Engine's Rubidium Wu shows you how you can evenly light two subjects, whether for an interview or dialogue scene, using only two or three lights. Check it out below:
So, why is cross keying so great? Well, it's incredibly economical. What it does is effectively gives each of your lights a dual purpose of acting as the far-side key light for one subject while acting as the kicker or backlight for the other, meaning you'll need half as many lights to light your scene.
Now, if you like the edgy, cinematic, high-contrast look that this setup produces, then great! You've just lit your scene with only two lights. However, if you want a softer, more even look, you can add a third light to serve as a fill for both of your subjects by placing it perpendicular to them and running it through some diffusion to smooth out the shadows on their faces.
With this lighting setup, whether you're using two or three lights, you'll be able to get most (if not all) the coverage you need for your interview or dialogue scene, including a medium two-shot, as well as close-ups of each subject. Depending on the placement of your lights, you may also be able to get some over-the-shoulder shots as well.
Have you lit scenes with cross key lighting before? Share your cross key tips and tricks down in the comments below.