Good News! This is the image of the upcoming Tamron 100-400mm F/4.5-6.3 Di VC USD lens, first leaked at the Nokishita. It is expected to be announced very soon!
This is a full size compatible telephoto zoom lens called Model A035 for Canon and Nikon mounts and the price would be about the same as Sigma 100-400.
Read More Tamron Lens Rumors