Ideally, a hydrogen fuel-cell vehicle has no environmental impact. Energy is produced by combining hydrogen with oxygen pulled from the atmosphere, and the tailpipe emission is water. The hydrogen fuel could come from a number of sources (Iceland recently started pulling it out of the ground).
A fast shutter speed such as 1/400th of a second will produce a series of crisp frames that have a choppy look when played back. A slow shutter speed such as 1/30th of a second, on the other hand, will produce a series of slightly blurred frames that have a smoother look when played back.
speed. 1  Also called film speed. the sensitivity of a film or paper to light, measured by an ASA or DIN index, which assigns low numbers to slow film and higher numbers to faster film. 2  Also called shutter speed. the length of time a shutter is opened to expose film. 3  the largest opening at which a lens can be used.