How does a camera work?

Welcome! I'm so excited to help you unpack the magic of how cameras capture a slice of time and turn it into a permanent memory.

Before we dive into the physical science of light and lenses, I'd love to know what kind of camera you are most interested in learning about. Are you hoping to understand the camera built right into your smartphone, a dedicated DSLR or mirrorless camera, or perhaps the vintage charm of a classic film camera?

Smartphone cameras

Awesome! Smartphones are absolute marvels of engineering, essentially squeezing what used to be a backpack full of heavy camera gear into a device less than a centimeter thick. Let's look at how they manage this squeeze, starting with how light physically enters your phone.

Squeezing Lenses into Ultra-Thin Phones

When you look at a traditional , it has a long, protruding lens. This is because glass lenses need physical space to bend and focus incoming light rays so they land perfectly on the sensor. If you don't have that physical depth—like in an ultra-thin smartphone—the light won't focus, leaving you with nothing but a blurry mess. To overcome this, smartphone manufacturers don't use a single thick piece of glass. Instead, they stack 5 to 8 microscopic, specially shaped plastic layers (called elements) right on top of each other. These elements work like a highly coordinated relay team, bending the light sharply and rapidly within a space of just a few millimeters.

Cross-section optical comparison between a deep DSLR camera lens chamber and a compact smartphone lens chamber.

As you can see in the visualization, the smartphone's miniature lens stack has to bend the light aggressively over a fraction of the distance. Because these plastic elements are so tiny and must align with nanometer-level precision, even the slightest manufacturing error can ruin an image. Now, in a traditional camera lens, there are moving mechanical blades that open and close to change the size of the hole letting light in—the aperture. But how do you think smartphone cameras handle this when they have almost zero physical space to move mechanical parts?