Digital Camera Fundamentals
A useful glossary to help you decode some of digital's terminology
As technology continues to expand, so does the vocabulary describing it. To help you stay on top of the field, we've decided to squeeze in an occasional glossary page of industry terms for a quick refresher or maybe even as a first-time explanation. For the first Fundamentals entry, we've zoomed in on digital camera terms.
Aberration Optical imperfections within a lens that cause distortions in the image. Most aberrations can be minimized through the use of corrective elements within a lens design.
APO (Apochromatic) Lenses that use internal elements to bring all colors of the visible spectrum to a common point of focus, creating a sharp image, are referred to as APO lenses.
Bit-Depth Also referred to as color depth, bit-depth determines the maximum number of colors that can be represented at a time. Camera sensors typically have 12-bit-per-channel color (red, green and blue) for a 36-bit image (which JPEG compression reduces to 8 bits per channel). Although more bit-depth is preferable, there are diminishing returns beyond 8 bits per channel. Image file sizes increase dramatically, and the increase in image quality may not be worth it for many photographers.
CCD (Charge-Coupled Device) An electronic image sensor for digital cameras. Most digital cameras are built around CCD sensors.
CMOS (Complementary Metal Oxide Semiconductor) A sensor technology that encompasses all required camera circuits on a single chip. Because a CMOS sensor requires less power and generates less heat than a CCD-based system, many large, high-resolution digital cameras use CMOS technology.