Some folks have asked about my stacking the Kenko 1.4x TC and 2.0x TC on the 400 5.6. We finally got some sunshine, so I have some pics shot today from outside my office in good light. These were shot handheld. The first is the shot using a 50mm lens, just to give you an idea of the scene as it looks to the naked eye. The next is the shot with the 400 5.6 and stacked TCs, just reduced in size to fit here. The third is a non-reduced 800x600 100% crop from near the center of the image.
50mm Shot
Stacked TCs (1120mm, f16, ISO 1600, manual focus)
100% Crop