Assertion: focal ratio | /r/CapableOf | vary optical power per unit area
Facets:
value: in the image
type: LOCATION
value: in photography
type: LOCATION
Source sentences:
text: In photography the focal ratio varies the focal-plane illuminance (or optical power per unit area in the image) and is used to control variables such as depth of field.
text: In photography the focal ratio varies the focal-plane illuminance (or optical power per unit area in the image) and is used to control variables such as depth of field.
text: In photography the focal ratio varies the focal-plane illuminance (or optical power per unit area in the image) and is used to control variables such as depth of field.