The Gel Drawer Most Photographers Never Open

Every lighting kit I’ve seen in a rental house has the same thing: a neat stack of CTO and CTB corrections at the front of the gel drawer, and then a mess of colors shoved behind them that nobody touches. Full CTO for tungsten matching. Half CTB for a cooler key. That’s where most photographers stop, and I understand why. Correction gels have a clear purpose. Creative gels feel like a decision you can get wrong in a way that ends up on a magazine editor’s desk.

But color is just another ratio. Once I started treating gels the same way I treat light output, metering them against each other and writing the results down, the mystery collapsed. This is what I actually do in my studio in Los Angeles, shoot after shoot, and it’s worth walking through the mechanics of it carefully.

Why Color Temperature Is Only Half the Story

A gel does two things simultaneously and most people only think about one. It shifts the color of the light, yes, but it also cuts output. A Rosco Supergel 27 (Medium Red) will cost you roughly 1.5 stops of light. A Lee 101 (Yellow) cuts about half a stop. That difference matters when you’re balancing a gelled rim light against an ungelled key.

The physics here is simple enough. Colored gels are transmission filters. They absorb wavelengths they don’t pass, and that absorbed energy doesn’t disappear, it just doesn’t reach your subject. Denser colors absorb more, so they cut more. If you ignore this and meter only your key light before gelling your rim, you’re going to pull up your test images and wonder why the rim has disappeared.

My habit is to meter every light twice: once bare, once gelled. I write both numbers on the masking tape label I put on each stand. When you can look at a stand and immediately see “Key: f/8, Rim gelled: f/5.6,” you stop chasing exposure in post.

Building a Two-Color Setup That Actually Works

The setup I return to most often for beauty and fashion work is a complementary color split: a cool key against a warm rim, or vice versa. It reads as intentional on skin without looking like a film student’s thesis project.

Here’s the exact recipe. Key light is a Profoto B10 through a 2x3 softbox, ungelled, set to f/8 at ISO 100, 1/125s. Rim light is a bare Profoto B10 with a Lee 204 (Full CT Orange) gelled over the head, dialed up to compensate for the approximately 1.3-stop cut, landing at f/5.6 metered at the subject’s shoulder. Background light is a small strobe bounced into a white wall, fitted with a Lee 079 (Just Blue), set to f/4. That cool wash on the background keeps the warm rim from making the whole frame look like a sunset.

The ratio of key to rim is 1.3 stops. The ratio of rim to background is 1.5 stops. Those numbers keep the gels from fighting each other. If the rim were at f/8 and the key were also at f/8, you’d get a muddy middle ground where neither color wins.

How I Test a New Gel Before It Goes on a Paid Shoot

I test every new gel the day it arrives. I have a foam head on a stand in my studio for exactly this purpose. I shoot it at three different output levels, write the stop loss in my lighting journal alongside a swatch of the gel taped directly to the page, and note whether the color reads differently under the modeling light versus the strobe. Some gels shift noticeably between continuous and flash, particularly in the red-orange range. The Rosco 19 (Fire) looks almost amber under a modeling lamp and reads as a hard red under strobe. If I hadn’t tested it, I would have placed it wrong on a beauty shoot and been confused about the result.

The journal habit started practically. I was early in my career, shooting an editorial for a regional fashion magazine, and I used a gel combination I’d eyeballed from a tearsheet without testing any of the output values. The whole shoot ran warm in a way I couldn’t fully correct in Lightroom without destroying the skin tones. The editor called. It was not a pleasant conversation. After that I treated every gel choice like a recipe that needed to be written down before it went into production, not after.

Gels That Earn Their Place on a Commercial Set

I keep about thirty gels in my kit, but six do most of the work.

Lee 201 (Full CT Blue): correction use, but also excellent as a rim on darker backgrounds. Cuts 1.8 stops, so dial up accordingly.

Lee 204 (Full CT Orange): the most useful warm gel I own. Works as a practical lamp simulator for editorial interiors. 1.3-stop cut.

Rosco 43 (Deep Amber): warmer than 204, almost golden. Good for hair lights on dark skin tones where CTO reads as too clinical.

Lee 079 (Just Blue): a soft cool. My background light default. Only about 0.5 stops of cut, which makes it easy to balance.

Rosco 27 (Medium Red): use sparingly. It dominates. Best as a practical background accent, not a skin-adjacent light. 1.5-stop cut.

Lee 135 (Deep Golden Amber): hair and shoulder rim on fair skin. Reads like late afternoon sun without looking theatrical. About 1.2 stops cut.

All of these are available in sample packs from B&H for under $30. Buy the pack, test the whole thing, keep what you use. Gels degrade over time from heat, so replace any that have faded or cracked, especially if they’re sitting close to a tungsten source.

The Single Thing That Changes How You Use Gels

Meter every gelled light independently, write the number down before the subject walks in, and stop trusting your eye to tell you whether the color is reading at the right intensity. Color is seductive and your eye adjusts to it faster than you think. The meter doesn’t.