Assertion: camera's lens | /r/HasProperty | focused at infinity
Facets:
Source sentences:
text: Strictly, the Principal Distance is the distance mentioned above (i.e. distance from imaging plane to the lens optical sensor), and the focal length is the principal distance when the lens is focused at infinity.
text: This printed number is actually its nominal length or the principal distance when the lens is focused at infinity.
text: A lens that has a 50mm nominal focal length (so a 50mm principal distance when focused at infinity) might in fact have a 100mm principal distance when focused at a few inches!
text: Instead, focal length is measured from the rear nodal point—which, along with the focal point, is one of the cardinal points in Gaussian optics—to the focal point while the lens is focused at infinity.