Commlite CM- EF-FX Booster Lens Mount Adapter for Canon EF To Fujifilm X Pro 2 3
If your lens is 50mm Focal lense with our 0.71x Booster Adapter Mount, then 50mm x 1.6 x 0.71=56.8mm, Equivalent to expand the aperture by one stop! If your lens is 50mm Focal lense, then: 50mm x 1.6=80mm.