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).
4) Fast, Slow and Long Shutter Speeds. Fast shutter speed is typically whatever it takes to freeze action. For me, it is typically above 1/500th of a second for general photography and above 1/1000th of a second for bird photography. NIKON D700 @ 420mm, ISO 450, 1/2000, f/5.6.
If you want to photograph something that is moving, you need a fast shutter speed. 1  Use 1/500 for general photography of everyday events, sports, and subjects. 2  Use 1/1000-1/4000 when shooting subjects that are extremely fast and up close. 1/1000-1/2000 works well when photographing birds. Typically only the denominator is marked on the camera. 2  For example, 125 means 1/125 second. 3  Some cameras allow you to take photos at a shutter speed in full seconds, such as 1, 2, or 10 seconds. 4  This is used for low light photography and a lot of movement.