I kept blowing highlights on my subject’s face while the background went flat and lifeless. Same shot, same location, same time of day. I’d fix the exposure for the face and lose the background. I’d expose for the background and my subject looked like a ghost. I knew it was a light problem, but I couldn’t articulate exactly why it kept happening or how to fix it at a mechanical level. Then I watched this short from Joel Grimes and something clicked.

In this Joel Grimes tutorial, he cuts straight to one of the most overlooked relationships in photography: how the direction and quality of light interacts with your lens focal length to create (or destroy) dimension in a portrait. It’s a short video, but it’s dense. Here’s what he’s actually teaching.

Why Light Direction Is the Variable You Keep Ignoring

Grimes makes the point that most photographers obsess over gear, including lens sharpness, megapixels, sensor size, when the single biggest variable in any portrait is where the light is coming from and how hard or soft it is. He’s not being contrarian for the sake of it. He’s pointing at something real: a technically sharp image with flat lighting looks worse than a slightly soft image with beautiful directional light. Every time.

The core idea he’s working from is that light needs to cross your subject’s face at an angle to create shape. Front-facing light, the kind you get from an on-camera flash or shooting directly into midday sun, kills dimension. Side light, even partial side light, wraps around facial features and creates the shadows that make a face look three-dimensional rather than like a passport photo.

The Ratio That Actually Matters (And How to Read It)

Grimes talks about the light-to-shadow ratio on the face as the defining characteristic of a portrait’s mood. A very low ratio, meaning minimal shadow, looks flat and commercial. A higher ratio, where you have strong shadow on one side of the face, creates drama. He’s not giving you a single “correct” number here. He’s giving you a thinking tool.

In practical terms, he’s describing the difference between a 2:1 ratio, where the lit side is roughly twice as bright as the shadow side, and something closer to 4:1 or higher, where the shadow side drops significantly. For softer, editorial-style portraits, you want to stay in that lower range. For moody, character-driven work, you push toward the higher end. The lens comes into this because a longer focal length, say 85mm or 135mm, compresses the scene and makes your light source appear relatively larger against the subject, which softens the transition between light and shadow. A wider lens exaggerates that transition and tends to make lighting look harsher.

Translating This to Your Lens Selection Before You Even Shoot

Here’s the practical workflow I took from his video. Before I set up a shot now, I’m asking two questions in order: where is my light coming from and what is its quality, and then, which focal length will work with that light rather than against it?

If I’m working with a single hard light source and I want it to look dramatic but controlled, I’ll reach for something longer. The compression softens what would otherwise be a brutal shadow edge. If I’m using a large diffused source and want to preserve that soft wrapping quality, a wider lens in close can actually work in my favor because it exaggerates the sense of the light enveloping the subject.

Grimes is essentially arguing that lens choice is a lighting decision, not just a composition decision. That reframe is useful.

Where I’d Push Back (Slightly)

I’ll be honest: this framework works cleanest in a controlled environment. Outdoors, especially in the kind of mixed and unpredictable light you find at midday in a city, the relationship between focal length and light quality gets messier. I’ve shot in downtown Denver at noon with an 85mm trying to work with window spill from a glass building across the street. The light was interesting but inconsistent, and no amount of focal-length thinking fully compensated for clouds passing or the light angle shifting between frames.

My addition to Grimes’s framework: when the light is chaotic, position is more important than focal length. Get your subject into a spot where the light is consistent and directional first. Then choose your lens. The lens choice amplifies what the light is already doing. It can’t rescue light that isn’t working.

The Single Habit That Will Change Your Portraits

Stop treating exposure and light as separate problems from lens choice. They are the same decision made at different steps. Get in the habit of assessing light direction and quality before you pick up any lens, and let that assessment drive your focal length selection.

Watch the full video from Joel Grimes for the visual demonstration. Seeing him point to actual light and shadow on a face while explaining the ratios makes the concept land in a way that’s hard to get from text alone.