Photography root derives from Greek roots "Photo", which means light, and "graphics" or means to write this writer. Photography is all about light and how to interact with him. Two basic functions of an SLR camera accomplish this through the aperture and shutter speed.

Shutter speed refers to the amount of time that the film, or in case of a digital SLR, how long the image sensor is exposed to light. Depending on the camera's shutter speeds from 30 seconds to 1 / 8000 rangeSecond. Some cameras have a "bulb mode, the user to manually open and close the shutter allows a switch.