FIGURE C

This is only a small subset of my rather excessive lens collection. Click picture for a larger image.

In future articles, we'll talk more about the different elements of the optics system and you'll become completely conversant in all the fun buzzwords of the photo industry.

Image-recording sensors
Once an image is transfered into the inner workings of the camera via the lens, a digital camera needs to perform some action to "understand" the image and process it so it can be saved for later viewing. The first component involved in this process is the image-recording sensor.

In a digital camera, these sensors go by the acronyms CCD (charge-coupled device) and CMOS (complementary metal-oxide-semiconductor). Both of these components are integrated circuits, and CMOS is actually a very broad term describing a large class of integrated circuit types. CMOS-based sensors tend to use less power. Even more confusingly, some manufacturers describe their CCDs as CMOS-based.

In any case, the imaging sensor is the chip inside the camera that actually converts light into digital form, the core of the digital camera that converts an analog image into a digital file. By the way, it's the number of pixels the image-recording sensor can capture that determines a camera's megapixel spec.

At this point in our story, you've looked at the outside of the camera, you've learned a bit about optics and the lens, and you've seen how an optical image (basically light and dark shadow and color) traverses the lens to be recorded by an imaging sensor.

Data from that sensor is used in two ways: it becomes the image through an LCD (liquid crystal display screen) so you can preview your shot. And, that data, if you so choose, is sent to the storage mechanism within the camera.

The viewfinder
To compose your image, you need to see what you're going to shoot. Most lower-end digital cameras have an LCD screen that provides a small-screen preview of what you're going to shoot. Most also have a tiny viewfinder you sight through, to see and compose your shot, as shown in Figure D.

FIGURE D

This is a very tiny lens and it doesn't necessarily faithfully reproduce what the camera sees. Click picture for a larger image.

Many amateur photographers prefer the LCD screen, shown in Figure E, since they don't have to hold the camera tight against the face to take a shot. The LCD also often doubles as the camera's menuing system, allowing you to adjust your camera's settings.

FIGURE E

The LCD screen serves to help you compose the shot, review your pictures, and access the camera's menu. The image in the LCD is of Pugsley A. Bear. He's very anti-social and he bites. Click picture for a larger image.

Most professional photographers like to sight their shots directly through the viewfinder, since they can both get a more accurate shot and block out outside distractions while composing the photograph. As we discussed in "What's an SLR?" at http://www.connectedphotographer.com/issues/issue200404/00001275001.html, viewfinders in more expensive single-lens reflex cameras see exactly what the lens sees. Viewfinders in less expensive cameras are often cheap plastic lenses that view your from a slight offset from what the image-capturing lens sees.