From the Manufacturer
DT lens design
A more compact, lightweight lens designed specifically for the APS-size CCD imager used in the Sony Alpha DSLR-A100 camera.
Aspherical lens elements
To correct visual aberrations at wide-angle setting, enabling a lightweight lens to capture more visually accurate wide-angle shots.
ED (Extra-low Dispersion) glass
To reduce chromatic aberration at telephoto extension, correcting certain wavelengths of light for sharp, clear images with well defined colors.
Because aperture blades form a near circle at the wide openings used for low-light shots, spot-light sources have a pleasing circular defocused effect.