The Language of lenses

Back in the Middle Ages, in a quiet monastery in Venice, a monk noticed something—his eyesight just wasn’t as sharp as it used to be. By then, people already knew that glass could bend light in interesting ways, and they’d been using it in all sorts of tools. That monk’s problems with reading led to an idea: creating the first lens to magnify text. Eventually, someone added frames, and eyeglasses were born.

So yeah, lenses have been part of our lives for a long time. We’re so familiar with them now that, even if they seem complicated, most of us already get the basics—at least enough to use them in telling visual stories.

Lenses are simple, but why do they have this reputation for being complex, like something only a few experts really get? It's a bit like gravity. On one hand, we all live with it. But when we see these complicated equations describing it, it starts to feel way over our heads.

Think about any image, whether it’s a photo or a realistic painting. They all follow the same rules that lenses rely on. For example, we know without really thinking about it that things closer to us look bigger, and things farther away look smaller. That’s perspective. It’s how the lens in our eye works, sending an image to our brain that we’ve learned to figure out without effort. So when a photo plays with size to suggest depth, we just go along with it—it feels natural.

If all of this sounds pretty straightforward, and you’ve assumed lenses are these complicated tools, then good news: you already understand more than you thought.
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My name is Tal Lazar, and this is “Visium”, where we explore images, and figure out what makes them work. In this first series, we focus on images in movies.

If lenses are so simple, then why do they have this reputation for being complex—like something only a few experts really get? It's a bit like gravity. On one hand, we all live with it. We feel it pulling every day. But when we see these complicated equations describing it, especially in astrophysics, it starts to feel way over our heads. Still, the basic idea is something we all understand—we just don’t always realize that’s enough to start exploring deeper.

It’s the same with lenses. You might wonder why it even matters to know so much about them. Most cameras today come with a zoom lens. You twist the ring, and voilà, the picture gets closer or wider. Doesn’t seem like it needs much thought.

But hang on. At some point, you’ve probably asked yourself: what’s the difference between slowly zooming in and a dolly shot, where the camera actually moves closer to the subject? Or maybe you’ve noticed how different a close-up feels when it’s shot with a long lens from far away, versus a wide lens up close. The lens changes the feel of the shot, and that plays a big role in how we experience the story. That’s why lens choice is one of the most important decisions a cinematographer makes.

To help students understand this, photography teachers usually start them off with a fixed lens—with no zoom. This forces students to move around and see the effect of a lens in different distances. Teachers might also tell students to start with only using a "normal" lens. What’s a normal lens? Many people think that means a lens that sees the world like the human eye, but here’s the catch: our eyes see a much wider field of view, almost 180 degrees. That’s would be a very wide lens. A normal lens, typically around 50mm, has a narrower view. So why call it normal?

Take an SLR camera—that’s a standard still photography camera with a viewfinder and a mirror inside. The mirror lets you see exactly what the lens sees. That’s different from a rangefinder camera, where the viewfinder is set just above the lens, so you’re not looking through it directly.
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Now, with the SLR, hold it up to your eye and look straight ahead. Then, take it down and look at the same scene with just your eyes. If you’ve got a normal lens on that camera, things should look about the same size—not bigger or smaller than they appear to the naked eye. That’s what makes it "normal." Simple, right?

And just like that, we’re already digging into some core concepts—like field of view and focal length. If you’re a director, knowing this stuff matters. Lenses shape the image, and conversations about them are where directing and cinematography blend together. That’s why, on big sets, you’ll see the director and cinematographer standing by the camera together or using a special viewfinder with lenses to plan shots. They’re not just framing a shot—they’re creating the feel of the scene.
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When I studied cinematography, I was surprised by how little time we spent digging into lenses. Sure, you learn the terms and basic principles. But later I found out how cinematographers like Janusz Kaminski or Jess Hall asked to remove lens coatings to create a specific period look. Or how Kubrick used special lenses designed by NASA in Barry Lyndon to shoot entirely by candlelight. Or that Roger Deakins intentionally degraded his lenses in The Assassination of Jesse James to create a unique mood.

And that made me wonder—how far off am I from really understanding this? Is it actually that complicated?

When I started teaching at the American Film Institute Conservatory, my first class was the core technical course for first-year cinematographers. I wanted to build a lens workshop from the ground up—one that didn’t just scratch the surface. So I signed up for an optics class at MIT—not aimed at filmmakers, but at scientists and engineers. I picked up a bunch of technical books and talked to lens technicians and experienced cinematographers.
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The result was a seminar that starts from the basics—assuming you just have general knowledge—and builds all the way up to advanced lens testing. If you're looking for a deep technical dive into lenses, that course is now online on my website at learn.cinematicimpact.com.
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But here, we'll keep things focused on what filmmakers really need: the vocabulary and the big question at the heart of visual storytelling—how do you choose the right lens for your movie?

Let’s take a step back for a second—what is a lens, really? It’s a great question, and I always remind myself of that Einstein quote: “If you can’t explain it simply, you don’t understand it well enough.” I like to call this the "5-year-old nephew rule." Imagine your nephew asking what a lens is. How would you explain it without making him pass out?

Here’s what I’d say: a lens is a piece of glass that bends light. That’s it.

More technically, lenses are part of a group called optical devices—basically tools that control light. A mirror, for example, is another optical device. It changes the direction of light by bouncing it back, or reflecting it. A lens, on the other hand, bends the light by letting it pass through and slowing it down just a bit. That bending, caused by something called refraction, is what makes the lens do its work.
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Kind of cool, right? Once you get that, it’s pretty clear: lenses are all about light. So to understand lenses, you’ve really got to understand a bit about how light behaves.
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Now, here’s a curveball. Do we even need lenses for photography? Can a camera work without a lens?

Turns out, yes—we don’t need a lens to take a photo. Enter the camera obscura. It’s basically a sealed box with a tiny hole on one side. That’s it—no lens, no glass. Yet it can still project an image. It’s a strange idea, but totally real. You can even try it yourself. Use a cardboard box or dark a room with one small hole in the window, and you’ll see a mini version of the outside world projected on the opposite wall. How is this possible?

Alright, imagine you're standing in front of a sculpture—something big, let’s say the Discus Thrower. From where you're standing, you can see the whole thing. Now, picture yourself holding up a piece of paper between you and the sculpture. That paper represents our frame inside the camera—like a digital sensor or film. And let’s imagine it’s made up of tiny pixels.

In this setup, with nothing in the way, you can see the entire Discus Thrower, all the light reflecting from it gets to your eyes. At the same time, each imaginary pixel on your paper also gets hit by light bouncing off every part of the Discus Thrower. So far, nothing special is happening—just light bouncing around and hitting the paper.

Now, imagine there’s a wall between you and the sculpture, and that wall has a tiny hole in it. When you look through the hole, you can only see a small part of the sculpture—maybe just the hand or the head. If you move a bit to the left or right, you’ll see a different part. That hole blocks most of the light and only lets a thin slice through.

The paper you're still holding on your side of the wall also changes how it “sees” the sculpture. Instead of each pixel catching light from every part of the sculpture like before, now each pixel only gets light from one small point. Since each part of the statue reflects different colors and brightness, each pixel ends up with its own value—some brighter, some darker, some with different colors. And just like that, an image starts to appear—but only if the room around you is dark enough, and the sculpture side is well lit.

That’s the basic idea behind the camera obscura. The magic was made by adding a wall with a hole.

Congratulations—you now actually have a solid understanding of how cameras work, and more importantly, how lenses work. Not convinced? Let’s walk through one more example.
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Picture yourself still in front of that wall with a tiny hole in it, looking at the Discus Thrower. But now, you’re sitting on the floor. When you look up through the hole, what do you see? The top of the sculpture. That’s because light travels in straight lines, and you’re looking up. So, light from the statue’s head enters the hole and hits the bottom of your image, while light from the feet hits the top. That’s why images made by cameras—or your eyes, for that matter—are upside down. Your camera has a processor that flips the image for you. Your brain does the same thing with the image it gets from your eyes.

Now here’s another thing: the hole in the wall has to be really small to get a sharp image. A tiny hole lets in just a thin stream of light, which keeps everything in focus—but also makes the image very faint. Make the hole bigger, and yes, more light gets in, and the image gets brighter. But there's a trade-off: the image becomes blurrier. Each pixel on your paper no longer sees just one small part of the sculpture, but a slightly bigger chunk. So the light starts to blend, and you lose sharpness.

Sound familiar? In a real camera, the part that controls this balance between brightness and focus is the aperture.

This is the basic principle behind cameras and lenses. If anything feels a little fuzzy, don’t worry—you can always listen back or try it out yourself. Just use a cardboard box and you should be able create a camera obscura yourself. It’s a simple way to see the magic for yourself.

This brings up one last question: if a little hole in the wall does such a great job, why do we even need lenses at all?

First off, you can use a pinhole with your camera too—there are pinhole caps made for most cameras, and yeah, you can take photos without using a lens at all. But once you try it, you’ll notice some big limitations.

For one, the hole has to be really small, which means hardly any light gets through. That makes shooting in low light impossible. Even taking pictures indoors can be tricky. You’ll get the best results on a bright, sunny day. And even then, you’ll need a long exposure to make the image bright enough. That’s okay for still photography, but if you're shooting video—where each frame has to be exposed at least 1/24 of a second—it's not very practical. You just won’t get enough light for a clean image.

Then there’s the issue of control. With a pinhole, you can’t zoom in, can’t zoom out—you can’t change the composition much at all. The angle you see is pretty much fixed.

This is where lenses come in. They give us real control over the image. You can make the frame wider or tighter. You can adjust brightness and depth of field using the aperture. You can choose exactly where the focus should be. And maybe most importantly, you can shoot in much lower light because a lens gathers and focuses more light onto the camera sensor than a pinhole ever could.

All of that—focal length, focus control, light gathering—these are core functions of a lens. Lenses don’t just let light through—they shape it.

Light is a big topic—we’ll dig into it more in a later episode—but for now, let’s just stick to what happens when light travels through space and hits something. Basically, three things can happen:

1. It can be absorbed. Think about closing the blinds during the day. No light gets into the room, right? That’s because the blinds are absorbing a lot of the light. And if you touch them after a while, you might notice they’ve warmed up. That’s because when light is absorbed, it turns into heat.
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2. It can be reflected. The blinds might also bounce some light back. All objects reflect light to some degree. Dark objects—like a black T-shirt—reflect less. White or lightly colored things—like snow—reflect a lot more.
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3. It can be transmitted. Some materials let light pass through. Like glass. That’s called transmission.

Now, when we think of lenses, we usually imagine they just let light through—just transmit it. But real lenses aren’t perfect. In fact, all three things—absorption, reflection, and transmission—happen at the same time. That’s why a window can also get hot in the summer—it’s absorbing some sunlight. And if you’ve ever looked at someone’s eyeglasses from the side, you’ve probably seen light bouncing off the surface.

Same thing happens with a camera lens that has more than one glass element inside. Light can reflect inside, between the different glass elements. When that happens, you can get glares or lens flares—those streaks or spots of light you sometimes see on screen.

Lens manufacturers use special coatings to reduce reflections, and that’s why when you look at the reflection off a lens, it sometimes looks blue or orange. It’s one of the key differences between modern lenses and older ones—modern coatings help reduce internal reflections so the lens can create a cleaner image.

But sometimes, cinematographers want the opposite. For Saving Private Ryan, Janusz Kaminski had Panavision remove the coatings from the lenses. The goal was to mimic the look of older lenses used during the time period of the film—without actually relying on vintage lenses. This kind of creative choice shows how technical knowledge about lenses can become useful to shape the look and feel of a story.

And we’re only getting started. Up next, we’ll dive into one of the most important parts of lens selection: focal length. What it is, how it works, and why it matters when telling a story with a camera.

If that sounds interesting, make sure to subscribe, leave a review, and join me for more as we keep exploring the art and craft of visual storytelling—and how filmmakers bring images to life.

If you have any thought, an example that wasn’t mentioned or a question, feel free to reach out—just email [email protected] . You can also check out my book at TheLanguageofCinematography.com.

Thanks for spending time with me today. Goodbye!