Continuing its trend of delivering a more upscale line of lenses than it had when Tamron introduced its original dSLR full-frame mount SP 150-600mm F/5-6.3 Di VC USD three years ago, the company plans to ship its vastly updated G2 versions shortly. It's got the modern metal build of Tamron's latest lenses, plus newer coatings (including a protective fluorine coating on the front element) and a new optical design to better handle high-resolution sensors; improved image stabilization with the addition of a panning mode; an ultrasonic motor for faster autofocus; and the ability to focus almost 20 inches or about half a meter closer than its predecessor. There's also a new zoom lock.
The Canon EF and Nikon FX versions of the SP 150-600mm F/5-6.3 Di VC USD G2 (Model A022) are slated to ship in Japan on by the end of September -- the Nikon model adds an electromagnetic diaphragm now that its cameras support it -- followed by US shipping. A Sony A mount version will come at some unspecified later date. The price will be $1,400 (directly converted, approximately £1,065 and AU$1,860); the current version costs about $1,000 (£740, AU$1,500).
Tamron also has a new pair of teleconverters in Canon and Nikon mounts to extend the reach of that lens, a $420 1.4x (TC-X14) and a $440 2.0x (TC-X20). They're on the same shipping schedule as the lens. Direct conversion of those prices are roughly £319 and £335, and AU$560 and AU$585.