The Digital Camera: an Introduction

In the summer of 1826 Joseph Nicéphore Niépce pointed his camera toward the buildings and trees outside the window of his second-floor workroom in the French commune of Saint-Loup-de-Varennes. The camera was a simple device by modern standards: a single lens focused light onto a 20 x 25 cm pewter plate that was coated with a tar-like form of petroleum called bitumen. After Niépce exposed the plate for eight hours with light focused from the scene, he washed away the regions of bitumen that were not hardened by the light and successfully developed the world’s first photograph.

Joseph Nicéphore Niépce's first photograph. (National Geographic's Milestones in Photography)

Niépce’s camera was primitive, but his idea of exposing a chemically treated plate or film with light and later washing away part of the chemical coating to develop the picture was the hallmark of photography for nearly 150 years. But in December of 1975, a young engineer named Steven Sasson presented his supervisors at the Eastman Kodak Company with a device that he described as an

“odd-looking collection of digital circuits that we desperately tried to convince ourselves was a portable camera.”

Sasson’s contraption weighed about eight pounds, used 16 nickel cadmium batteries, and was distinctive in its use of a new type of electronic apparatus called a charge coupled device (CCD) imaging array. The CCD allowed the camera to capture an image with 100 rows and 100 columns of picture elements, or pixels. The 10,000 pixel values captured by the CCD were stored on a portable digital cassette and later displayed by a standard television set. The complete process of recording and storing an image took twenty-three seconds, but when the first image of a reluctant lab assistant was captured with this one one-hundredth mega-pixel camera, the new field of digital photography was born.

Sasson's digital camera.

The process we use for taking photographs with today’s digital cameras is much simpler than the ones developed by Niépce and Sasson. We point and we shoot. But the technology inside our camera is considerably more elaborate than Sasson’s toaster-sized digital prototype. Our images are formed with complex lenses whose surfaces are polished to tolerances much finer than the diameter of a human hair. Our cameras acquire tack-sharp focus within a fraction of a second through the aid of microprocessors that contain millions of transistors. Sophisticated sensors record the scene, and liquid crystal displays (LCDs) allow us to view our pictures immediately. We use memory cards to store hundreds or thousands of photographs that we later print for framing or transfer to permanent storage on our computer. In short, our digital cameras are technological marvels.

The technology inside our cameras is so good that novice photographers can – and often do – capture stunning photographs by knowing nothing more than how to point a camera and press its shutter button. Eventually, however, nearly all photographers encounter a substandard situation with lousy lighting, faulty focus or some other technical trouble. In times like these, a thorough understanding of the technologies that make a camera work can spell the difference between delight and disappointment.

In subsequent posts, we’ll explore and explain much of the science and technology that enables digital cameras to enact their magic.

© 2011 Timothy Schulz

The Digital Camera
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