Glossary of Digital Photography Terms

Glossary of Digital Photography Terms - Part 6

CCD – (stands for Charge-Coupled Device) is a type of sensor commonly found in consumer level cameras.
CMOS – (stands for Complementary Metal Oxide Semiconductor) is a type of sensor commonly found in more professional level cameras.
Diffuser – is a piece of opaque plastic that sits over the top of a flashgun. It’s job is to soften the light from the flashgun, and therefore reduces harsh shadows caused by a ‘bare’ flash.
Prime Lens – is the opposite of a zoom lens, prime lenses have one fixed focal length. They represent the best quality of lens available, but have the big drawback in that they cannot ‘zoom in’ to a subject.
Purple Fringing - is an undesirable purple “rim” that surrounds areas of high contrast in a digital image, very obvious when photographing people against a bright (but not deep blue) sky.
Shutter Delay - Traditionally, the shutter opened when you pressed the camera’s button, exposed the film behind the shutter, and then closed again; covering the film back over in the process. With electric sensors the “shutter” is controlled by the camera’s computer. A short shutter speed means the sensor is charged for a fraction of a second. For longer shutter speeds, the sensor is kept charged for longer.
Dynamic Range of a Sensor - is defined by the largest possible signal divided by the smallest possible signal it can generate. The largest possible signal is directly proportional to the full well capacity of the pixel. The lowest signal is the noise level when the sensor is not exposed to any light, also called the “noise floor”.
Interpolation - is an imaging method to increase (or decrease) the number of pixels in a digital image. Some digital cameras use interpolation to produce a larger image than the sensor captured or to create digital zoom.
Optical sharpness - is defined by the quality of the lens and the sensor.
Software sharpness - is creating an “optical illusion” of sharpness by making the edges more contrasty.