[davidmanze]

I don't really mean to torment Klaus (and have sharp / heavy objects thrown in my direction), but what about the Sigma 150-600 C? This one is the real competitor to the Tamron, not the Sport one (which is 2x the price / 1.5x the weight).

Poor Klaus is still in mid recuperation, what with all that walking back and forth to the resolution charts, the thought of a further tele-zoom test would probably push him over the edge.

 Best settle for reading the Lenstip review which settles the issue with a chart showing the differences between the two, at the long end (the important end) the Tamron pips the C, only the shorter end does the C get the better of it. Of the three reviews, Lentip,Ephotozine and SLR the Tamron beats the C, I know I agonized over the reviews before ordering the Tamron. 

  The Sport won conclusively though.   Ephotozone's review the Tamron's center at 600mm touched excellent!

 

 This shot of the yellow wagtail is shot at 600mm F11, it really is tack sharp.(slight crop)  D750