Encyclopedia > Angular aperture

Article Content

Angular aperture

The angular aperture of a lens is the appearant angle of the lens aperture as seen from the focal point[?]:

<math>a = 2 \arctan \frac {A} {2 f}</math>

where <math>f</math> is the focal length, and <math>A</math> is the diameter of the aperture.

Featured Article

Brazil

... ticket by popular vote for four-year terms. The president has extensive executive powers and is both head of state and head of government and he also appoints th ...