Lighting gels: What are they and how do they work?

Proper lighting goes a long way towards selling your project to viewers. Dynamic lighting allows your visuals to tell a visually captivating story, elevating your production to an entirely new level. A great way to do this is through lighting gels.

What Gels Do

Lighting gels serve a number of purposes, but the ultimate goal of any gel is to change a light’s color temperature. Sadly, retinas and camera lenses don’t see color the same way. Thus, managing color temperature, so images on film look like we expect them to, is a tricky balance filmmakers have dealt with since the advent of motion pictures.

Gels let you tweak the color temperature on your lighting rigs to make them warmer (more yellow/orange light) or cooler (bluer tones) depending on the needs of your scene. Used properly, gels add more realism to your video while bringing in another level of visual detail to the story.

Used properly, gels add more realism to your video while bringing in another level of visual detail to the story.

Plus, if you’re using a green screen, there are also gels to limit color spill. To illustrate, spill happens when light bounces off your green (or blue) screen and splashes onto your subject or actors. While it may only be a hint of green, it makes your post-production work — keying out the green screen — much more difficult.

Consequently, gels alleviate this spill by keeping the light intensity down — a cheaper alternative to reflective panels and umbrellas. The can also balance out the greens/blues with counter colors to keep them from being noticeable on camera. While a little bit of a spill may not seem like a big deal on the set, it’s a massive headache in post-production.

Tinted lighting gels help set the mood for your video
Tinted lighting gels help set the mood for your video

Gels serve these very practical purposes, but they also allow you to get creative. More than balancing things, gels can drastically alter the overall color palette of your scenes. For example, say you’re recording a project with science fiction themes. Using deep blues/violets create a stark neon, cyberpunk feel to your scenes (e.g. Blade Runner 2049).

Moreover, viewers may not consciously recognize the lighting choices, but it’s another layer of immersion into your story. Similarly, using colored gels to highlight important character moments or emphasize emotional points allows you to visually tell a story beyond the dialog.

This is all true, even if you’ve made the jump to LED lights over tungsten. While many LED rigs have built-in color temperature options, gels are still your best option for stylized and natural looks. Even with the best LEDs, there are still plenty of situations where gels can more easily give you the results you need.

Types of Lighting Gels

There are different gels for different purposes. So, knowing what each gel does and the best time to use them is crucial to them being an effective part of your project. There are four main types:

CTO – Color Temperature Orange brings down the intensity of daylight by filtering out the blues on the spectrum. Where daylight is considered to be around 5600 Kelvin, CTO gels your lighting set up down to 3200K. This will closer match indoor lighting sources.

CTB – Color Temperature Blue is the opposite of CTO, used instead to give your tungsten lights a more “daylight” appearance. These are great for outdoor scenes, or anywhere you want to have natural/daylight lighting in place.

Minus Green – This Magenta gel strips out the green and gives off a more natural indoor light. If you find yourself filming inside offices with fluorescent lights, this is a must. Minus green also helps with green screen color spill.

ND – Neutral Density gels are all about controlling light intensity. They’re like sunglasses for your lights, pulling the brightness down without affecting the colors. Primarily, these are used for covering windows to block out the sun coming inside.

One Size Doesn’t Fit All

Gels are incredibly helpful, but like all things in video production, no single tool is perfect for every situation. All gels have multiple gradations to choose from and you may need to test a few before finding the right one for each scene.

Thankfully, gels are among some of the cheapest pieces of equipment you can purchase, with variety packs going anywhere between $15-$30. While some are more expensive depending on the size (Neutral Density especially), on the whole gels are relatively inexpensive and will last multiple shoots. Without price being a hindrance, there’s no reason to ignore the benefits of using gels for your lighting setups.

In the digital age it’s easy to fall into the, “we’ll fix it in post” trap for color correction. Yet, that’s a long and tedious process that often results in a compromise. Using gels properly can eliminate those headaches early on. Sure, they require a little more setup, but the time saved in post is more than worthwhile. Not to mention, you’ll get far more natural tones via gels on set than by trying to replicate them in the computer.

Jordan Maison
Jordan Maison
Jordan Maison is a writer and journalist, having studied film in college and covered all aspects of film for the past 15 years.

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