Leica 24-70mm f/2.8 Versus Sigma 24-70mm f/2.8: Is There a Difference?

While reviewing the Leica 24-70mm f/2.8, I was able to spend some time with a lens from Sigma that has been accused of being the exact same lens in a rehoused body. But is it?. Editor's note: The following evaluation is meant to be viewed after reading the full review of the Leica 24-70mm f/2.8, as most of the information below focuses on showing how the Sigma lens performs in comparison to those results and is written from the assumption that readers have familiarized themselves with the same assessment of the Leica lens.