What is an aspherical zoom lens?
An aspheric surface is a complex one not matching the surface of a large sphere. Older techniques for creating lens elements would have made aspheric surfaces more expensive, and very difficult to make. It was occasionally done, but at very great expense. A zoom complicates matters requiring many more glass elements to enable a continuous range of focal lengths. What the “hybrid aspheric” allows is fewer elements to correct for chromatic aberration ,the fact that light in different colors refracts at different angles. To keep it from spreading out in a lens, you have to correct for it with additional elements.
