I thought of our super moderator Daniel who works a subject while it is available and I went back to the spot of the plovers. I thought of getting as close as I can....so I added the 3 extension tubes I have between the 500mm lens and the 1.4 TC on one side and the camera on the other side. I am sore now...hours of crawling...but I have some nice images. Here is the first one. I left the light of the flesh to show how close I was. Comments are welcome.
1DMKIV
500mm+1.4TC-3 extension tubes-camera body=manual focus
ISO800
f:25
1/100
skimmer
BB and flash
Full frame
There's something about this that just goes against my grain. Perhaps too close? I never like to feel like I am imposing on the bird, and that's what I feel like here. (I know you used extension tubes, I'm just commenting on the "Feel" of the image.)