The Feynman Camera Primer

How Digital Cameras Really Work

From Photons to Pixels, and Why a $300 Camera Isn’t a $10,000 Camera

"Nature uses only the longest threads to weave her patterns,

so that each small piece of her fabric reveals the organization of the entire tapestry."

— Richard Feynman

Chapter 1: Catching Light

How a photon becomes a number

Every digital camera does exactly one thing: it catches photons and turns them into numbers. That’s it. Everything else—the megapixels, the frame rates, the image processing, the $10,000 price tag—is engineering detail around that one idea.

The Photoelectric Effect (Yes, That One)

Einstein won his Nobel Prize not for relativity but for explaining the photoelectric effect: when a photon hits certain materials, it knocks loose an electron. This is the basis of every digital camera ever made. A photon arrives, hits a silicon photodiode, and generates a tiny electric charge. More photons = more charge. The charge is proportional to light intensity. That’s your measurement.