On a cold foggy morning at Kabini. The mist was quite dense and visibility was extremely poor.
Had to bump up the ISO to insane heights (16000!!!), Wide open aperture (4.5), Exposure compensation +2.0 and the shutter at an alarming 1/125 on a boat, which had its motors switched off.
The 100-400 IS II ISM and the 5D Mark III were supported by a large bean bag.
Was not sure if the circular polarizing filter would have worked here as there was absolutely no sunlight and hence did not try using it.