Assertion: focal plane shutter | /r/HasProperty | driven by spring
Facets:
value: mechanically
type: MANNER
Source sentences:
text: The focal-plane shutter, located directly in front of the image plane, consists of a pair of overlapping blinds that form an adjustable slit or window; driven mechanically by spring or electronically, the slit moves across the film in one direction, exposing the entire frame in its sweep.