2 A B C D E F G H I K L M N O P R S T V W

Aperture angle

Angle that the lens can see in the direction of a given sensor measure.

The angles in horizontal, diagonal and vertical directions differ.
Please distinguish between the max. possible aperture angle and the actual aperture angle.
Actual aperture angles are influenced by the length of used extension rings,and even focus distances (because they are mostly achieved by simulating extension rings) max possible aperture angles aren’t
Changing the sensor size changes the actual aperture angle, max possible aperture angles aren’t
Datasheets of lenses usually show aperture angles for a given sensor size! Changing the sensor size changes the angles!
For lenses without distortion a lens that has the diagonal of the sensor as focal length has 53.1 degrees
A (no distortion) 6mm lens on a 1/3″ sensor,a 8mm lens on a 1/2″ sensor and a 16mm lens on a 1″ sensor have the same diagonal aperture angle of 53.1 degrees