The M.Zuiko Digital ED 17mm f/1.2 PRO. The ED-DSA lens possesses the characteristics of both ED (Extra-low Dispersion) and DSA lens1 elements, of which Olympus was the first manufacturer to successfully mass produce. The ED-DSA lens makes it possible to significantly reduce the number of required lens elements, resulting in a lighter product. This construction also effectively compensates for various types of aberrations that tend to occur on wide-angle lenses, such as comatic aberration, distortion, and colour bleeding on the image periphery (magnified chromatic aberration). Extensive use of special lenses incorporated into 15 elements in 11 groups makes outstanding imaging performance possible.