What would a fixed 2.8 aspherical lens be best for? It means the surface of a lens does not follow the contour of a perfect sphere. On my 50mm f/1.4 for example, the front element seems to have a dimple in it.
Aspherical lenses are not necessarily better or worse than 'regular' lenses. Some lenses are simply designed with aspherical elements because that was the most efficient way.
A fixed f/2.8 lens tells you that the lens is suited for low light photography. It also tells you that the lens can achieve shallow depth of field (massive background blur) if you want. And since f/2.8 zooms are expensive for this reason, it's usually also a sign of fantastic image quality and fast auto-focus speed. | 