Waiting for this video from you so thank you. I have both lenses and you are on point 100%. I m debating on selling the 200-400 but can't bring myself to do it because of always shooting in low light. Sun never shines here. The 100-400 is superb and bought it for hiking and scouting the wildlife preserves. The minute I twist on the beast 200-400;I'm quickly reminded how good that lens ism a monster plain and simple. Having that 1 extra stop definitely helps in low light and it produces the most amazing images. It's a tough one as the 100-400 is so good. Most photographers couldn't tell the difference even with a slight crop on a mkii image printed to a reasonable size as your images show. The fact it's a hard decision is a testament of the bang for the buck value of the mkii. Keep them coming. Really enjoy your channel. Steve

A good honest review

Good comparison

I won't buy either. To use either you will certainly need a tripod. A much smaller lightweight 100-300mm can be hand held. Much better for action shots.