Amber

Before I gave it back to its rightful owner, I wanted to test the 2x mkIII teleconverter on my 70-200/2.8L IS mkII.  For travelling this is an attractive combination - on paper - but I needed to see what the compromises were.  For this test I was able to use my ever-faithful "dumb blonde" as a model, and she even cooperated on this occasion.  This allowed me to use different focal lengths and apertures to see how the lens+teleconverter performed.  Here are some of the results.

As with the 300/2.8L, the combination is soft at f/5.6 but sharpens up considerably at f/8 - in the centre at least.  At f/11 it's sharp across most of the frame, but this means it's necessary to work at a reasonably high ISO in order to stop the shutter speed dropping.  All of these shots were hand-held, as it's bad enough combining a dog and a camera on a walk without adding a tripod too!  As with my previous tests, the 1.4x mkIII produces superior results, but there are times when the extra reach could well be valuable.