Assertion: lens | /r/CapableOf | produce same illuminance
Facets:
value: at the focal plane
type: LOCATION
Source sentences:
text: But compared to the 100 mm lens, the 200 mm lens projects an image of each object twice as high and twice as wide, covering four times the area, and so both lenses produce the same illuminance at the focal plane when imaging a scene of a given luminance.