What a strange and exciting time we live in! This is the new Tamron 100-400mm lens for full-frame DSLRs, in a Canon EF fit, mounted on the new Sony A7R III mirrorless camera, via a Sigma MC-11 adapter! Talk about worlds colliding! And it actually works too... (disclaimer: we've initially reviewed the lens on a Canon 5DS R) Read our in-depth Tamron 100-400mm F/4.5-6.3 Di VC USD review