Lens construction: 12 elements in 9 groups, with 1 SLD glass and 2 Aspherical lenses Compatible with high-speed autofocus Compatible with lens-based optical correction Mount with dust- and splash-proof structure Super Multi-Layer Coating Aperture ring Focus Mode Switch Round Type Lens Hood Designed to minimize flare and ghosting Stepping motor Supports DMF, AF+MF (for Sony E-mount only) Inner focus Every single lens undergoes SIGMA's proprietary MTF measuring system 'A1' 9-blade rounded diaphragm High-precision, durable brass bayonet mount Made in Japan craftsmanship