Canon EF 100mm f/2.8L is USM Macro Lens for Canon Digital SLR Cameras International Version (No Warranty) Lens Construction: 15 elements in 12 groups. Canon's first mid-telephoto macro "L" series lens to include Canon's sophisticated Image Stabilization Focal Length & Maximum Aperture: 100mm 1:2.8 Focus Adjustment: Inner focusing system with USM; full-time manual focus available. Filter Size: 67mm