AT2 Aspheric Technology

Many of Fujinon's HDTV and broadcast lenses feature Fujinon's AT2, which combines
the company's exclusive Aspheric Technology with a new inner focusing system to
greatly improve lens performance over conventional designs.
A single aspheric element reduces distortion at wide angles, improves corner resolution,
reduces glare and reflections, and allows chromatic aberration to be managed throughout
the zoom range, rather than simply optimized at specific points.
Aspheric elements gain their advantages from the way light passes through them.
Light passing through the periphery of a spherical element falls on a different
point on the focal plane than light passing through the center (spherical aberration).
This requires additional elements to correct. Since light passing through aspheric
elements focuses at the same point on the focal plane, additional elements are not
needed. Lenses with aspheric elements eliminate the additional weight and space
required by the corrective group of elements as well as their increased potential
for distortion, ghosting, and flare.