Both the Sigma 18-35 and Sigma 50-100 share the same construction features and the same level of quality. Particular to these Canon EF Mount Sigma cine zoom lenses, the lens’ mounts have been improved by strengthening the hole for the stopper with a separate part to minimize loosening over time and enhance long-term use. To learn more about each individual lens, please refer to their specific product pages: SIGMA 18-35MM T2 CINE LENS EF MOUNT - 210966 SIGMA 50-100MM T2 CINE LENS EF MOUNT - 693966