[Klaus]

If the existing 70-300 drops do the lower (price) tier, this could be more upscale than this, and way more compact than the 50-400.
I guess it is meant to mesh with the 17-50/4, like the 50-400.
My little bit of gripe is, would it hurt them (much) to go back to f/5.6 at the long end? Yeah, it's just 1/3 stop, but I thought as the scene evolves, lensese would be becoming faster, not slower.

The 17-50mm was a disappointment ... but yes, from a Tamron perspective, it would make sense.