weird bokeh on 100-400 II

Phoenixkh wrote in post #18477610
We don't quite have that "special" humidity you find in SE Asia.... but we get close here in Florida. It does make summer photography a challenge sometimes. Truth be told, we don't go out near as much in the summer months. I find the Spring bird rookeries around Florida to be tons of fun.. and it's usually only in the low to mid 80's.. so almost bearable for 3 or 4 hours.

I'm looking forward to some cooler temps. Two weeks ago, it was blazing hot, and I had an Osprey in a pine that I couldn't even fill the frame with my 600mm as it was so distant. Over a pond, mid-day. The heat haze was atrocious. It was like the bird and everything else was imaged through fractured glass. Gets really bad over hot water or hot wet grass (marsh) in the open sun the longer the lens gets (higher magnification) as the seeing is the limiter.

Very best,

It is possible to create the bokeh effects intentionally if you want to try to figure it out. It is subtle and it is not easy to predict how it will appear, though. It is typically seen most often in backgrounds with strong high contrast lines. With my 100-400 II, I seem to see it most often when at a shorter focal length than 400mm.

Here is an example that I shot about an hour ago just as an experiment. These are 1:1 views. I think you can see that the bright twig develops dark bands when out of focus. The effect is variously called "doubling" or "ghosting".

The 100-400 ii is not a master of bokeh and rendering may indeed get worse due to particular atmospheric conditions but the samples posted by the OP are really too extreme. I cannot find something similar from my thousands of pics shot with this lens.
If the OP was panning with a relatively fast SS that might explain the "doubling effect" we see in the image.