Parts of a DSLR

Many of us used film cameras in the past. What's different about a DSLR?

A DSLR is similar in almost all respects to a non-digital SLR except for the fact that a DSLR employs a digital sensor and memory instead of film (and has a host of electronics that non-digital SLRs did not need because they had no sensor).

All digital and non-digital SLRs have:
0) a camera body;
1) a viewfinder;
2) a mount to accept a lens;
3) buttons and dials to change exposure settings and other camera options; and
4) a shutter release button.

Many also have:
5) a flash receptacle to accept an external flash or flash extension cord and/or a small on-camera flash.

The primary difference between DSLRs and non-digital SLRs is the use of a sensor, memory, and associated digital wizardry instead of film. In non-digital SLRs, a film received an image transformed by a lens when the shutter quickly opened and closed. The film would be developed, depending on its type, into negatives (for subsequent printing) or positive slides.

In contrast, a sensor in DSLRs receives the transformed image and converts it to a digital representation. A processor in the camera then processes the digital representation and stores the processed image in memory. The processing can include enhancing the image (e.g., adjusting colors, sharpness, etc.) and converting the format (e.g., from a native "raw" format to a standardized format such as JPEG).

Once the camera has stored (either in raw or in JPEG) the image, the camera can generally display the image in an LCD display. If you want to be really fancy, many DSLRs can enable photographers to see images immediately on a connected computer as soon as the image is stored in memory. In this "tethered" mode, the camera is connected to a computer via a USB or IEEE 1394 ("firewire") cable and software executing on the computer can display every new image immediately.

Newer DLSRs (and almost every point-and-shoot camera made in the last decade) also have a "live view" mode in which the LCD display can display what the sensor "sees" even before the image is stored.

Thus, one of the main advantages of a DSLR is instant gratification. You can view the image as soon as you take it. Although you may not be able to judge some important features of your image accurately (e.g., focus or sharpness), you can check correct exposure, composition, and whether everything you wanted in the image made it in -- things that were impossible to do with film.