Panasonic LEICA DG VARIO-SUMMILUX 25-50mm/F1.7 ASPH. H-X2550F1. 7 Micro Four Thirds (MFT) camera lens for professional photographers and videographers Bright F1. 7 aperture is available across the entire zoom range of 25 50mm A stepless aperture ring and micro step drive aperture system ensure optimal, consistent light when zooming or panning The optical design achieves exceptional barycentric stability to minimize image shifts during zooming Dust splash freeze resistant design withstands heavy field use under