The Workings of a Digital Camera

You push the button, we do the rest. George Eastman, 1888, pitching the first Kodak camera

AND there was, indeed, a time when it was just that simple. I recall my father's Kodak. I don't know what happened to it after he died, and so it took some research on eBay to find out that it was most likely a Pocket Kodak 1 or 1A, which Eastman Kodak began selling about the turn of the century—the last century, like 1900.

It was not a fancy camera. The upscale Kodaks had red leather billows, polished wood rails for the lens assembly to travel as you focused, brass fittings, and lenses from Zeiss. Daddy's Kodak was serviceable, and a lovely creation in its own right. To take a picture, you looked down into a viewfinder that was a mirror set at a 45-degree angle. It had no motors. You cocked a spring manually and pressed a plunger at the end of a cable tethered to the lens to make the shutter snap open and shut. Focusing was a combination of guesswork and luck, although now that I think about it, I don't recall seeing an out-of-focus picture come out of the camera.

When not in use, the bellows —made of pedestrian black leather—and the lens collapsed into the case, which also held the roll of film. Despite its name, the Pocket Kodak would have been a tight fit in most pockets. But it wasn't a toy. It was meant to be carried and used anywhere.

The thing is, it took very decent photos. And it did so with few means to adjust exposure or focus —and with no opportunity at all to adjust settings we assume should be adjusted with today's cameras. There were no white balance controls, no bracketed shooting or exposure compensation, no depth of field to worry about, no flash or backlighting. You pretty much clicked the shutter and a week later picked up your photos from the drugstore. Today's cameras, with all their automation and intelligence, are very easy to use. But you couldn't blame a novice if the sight of so many knobs and buttons makes him suddenly grow weak. It's not so bad if you take all the controls leisurely and a few at a time. That's what we'll do here to familiarize you with the lay of the land before you embark into the deeper territory of how digital photography works.

Not your father's Kodak maybe...but it was mine.

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GETTING TO KNOW DIGITAL CAMERAS

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thering the Light

Here we're looking at two types of digital cameras. The small one is less expensive, so it doesn't have all the features found on the giant to its side. Both cameras, though, follow the same process when they capture a moment of time and a slice of space as millions of numbers that describe perfectly the shapes and colors that constitute a digital photo. Both cheap and expensive cameras start the process the same way—by gathering in light with all its shadows, colors, and intensities, and channeling it through its digital metamorphosis. Here are the parts of a digital camera that kick off the show by latching onto the light.

On/Off switch: It does run on electricity, after all.

Menu controls: Knobs or buttons that allow you to make selections from a software menu displayed on the LCD screen.

Viewfinder: Peer through this window to frame your picture. (See Chapter 4, "How Light Plays Tricks on Perception.")

On/Off switch: It does run on electricity, after all.

Viewfinder: Peer through this window to frame your picture. (See Chapter 4, "How Light Plays Tricks on Perception.")

Light meter: Measures the amount of light bouncing off a subject, information the camera's electronics use to expose the picture correctly. (See Chapter 5, "How Digital Exposure Sifts, Measures, and Slices Light.")

CHAPTER 1 THE WORKINGS OF A DIGITAL CA

Light meter system: More-expensive cameras use a system of light meters to measure light readings from specific parts of the subject.

Light meter system: More-expensive cameras use a system of light meters to measure light readings from specific parts of the subject.

Lens: Collects light, passing it through a small opening to focus on a type of microchip called an image sensor. (See Chapter 3, "How Lenses Work.")

Image sensor:

A microchip sensitive to light. It replaces film. (See Chapter 7, "How Light Becomes Data.")

Mirror: Reflects light so that the light coming through the lens is seen in the viewfinder. In some cameras, the mirror is replaced by a beamsplitter, a combination of prisms, which are blocks of glass or plastic that reflect light through the viewfinder and to other parts of the camera, such as the image sensor. (See Chapter 4.)

Lens: Collects light, passing it through a small opening to focus on a type of microchip called an image sensor. (See Chapter 3, "How Lenses Work.")

A Camera's Electronic Circuitry

Like the motherboard in a computer, cameras have printed circuit boards inside them that send electrical signals scurrying from one part of the camera to another, to control and synchronize the many functions of the camera.

10 PART 1

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GETTING TO KNOW DIGITAL CAMERAS_

ating the Image

When light first strikes the lens, it is incoherent light, or light that travels in all directions indiscriminately. The light might be no brighter than a shadow in a cave, or it might be the glare of the Sahara at noon. But that light is no more an image than mere noise is music. It's the role, mainly, of two parts of a camera — the focus and exposure systems — to mold light into an image that captures and freezes one momentary slice of time and place. In the digital world, new tools let us refine the photograph even further, but the photography still starts with the tools that get the pictures into the camera in the first place.

Menu controls: Knobs or buttons that allow you to make selections from a software menu displayed on the LCD screen.

Shutter button: A switch that, when pressed, triggers an exposure by locking autofocus and autoexposure and opening the shutter. (See Chapter 5, "How Digital Exposure Sifts, Measures, and Slices Light.")

White Balance button: Adjusts the camera so that, when the camera photographs a white object, it displays a "true" white regardless of how artificial lighting might introduce off-white hues. (See Chapter 5.)

LCD read-out window: Usually in combination with the digital control, this window tells you information such as the resolution, number of shots left, and battery power.

Infrared light source: The autofocus mechanism uses infrared rays that have bounced off the subject to determine the distance from the camera to the subject. (See Chapter 3, "How Lenses Work."

LCD read-out window: Usually in combination with the digital control, this window tells you information such as the resolution, number of shots left, and battery power.

Menu controls: Knobs or buttons that allow you to make selections from a software menu displayed on the LCD screen.

Light meter: A microchip that senses and measures the intensity of light striking it. (See Chapter 5.)

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Viewfinder: Peer through this window to frame your picture. There are many types of viewfinders, their accuracy improving as the camera's price rises. (See Chapter 4, "How Light Plays Tricks on Perception.

Flash: Produces an intense, brief flash of light when available light is too dim. See Chapter 6, "How Technology Lets There Be Light.")

Shoe and/or plug for external flash: Provides a way to synchronize the flash of an externally powered light with the opening of a camera's shutter.

Flash: Produces an intense, brief flash of light when available light is too dim. See Chapter 6, "How Technology Lets There Be Light.")

Internal light metering system:

Located near the prism, it measures light coming through the lens, which, compared to an external meter, provides a more accurate and versatile way to set exposure. (See Chapter 5.)

Shoe and/or plug for external flash: Provides a way to synchronize the flash of an externally powered light with the opening of a camera's shutter.

Focus ring: Lets you adjust the lens so it focuses best on objects that are a certain distance from the camera. (See Chapter 3, "How Lenses Work.")

Manual zoom control: Changes the Optical zoom factor of the lens, so distant objects seem closer or so the lens has a wider range of view. The control is usually a ring that manually adjusts the zoom or a rocker switch that transmits electrical signals to tiny motors that turn gears inside the lens. (See Chapter 4.)

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