Assertion: camera lens's length | /r/HasProperty | given
Facets:
Source sentences:
text: The simplest case is where lenses are placed in contact: if the lenses of focal lengths f 1 and f 2 are "thin", the combined focal length f of the lenses is given by
text: If two thin lenses are separated in air by some distance d, the focal length for the combined system is given by
text: In this case 1/u is negligible, and the focal length is then given by