That means that these types of lenses are usually not suitable for fast-moving objects which require short exposure times to freeze motion – see lens speed.
The amount of collected light can be increased by opening the angle of view, which is achieved with an even shorter focal length resulting in a wide-angle lens.
The advantage of this design is that it can be produced very inexpensively, more so than autofocus or manual focus systems.
The system is also effectively automatic; the photographer need not worry about the focal point for a given scene.
Fixed focus can be a less expensive alternative to autofocus, which requires electronics, moving parts, and power.