The purpose of these images was to push a Sigma 150-600 all the way out, and more important, test the image stabilization.
This lens does not seem to work like other Sigma’s, or Canon for that matter. The IS function is not as obvious in the view finder. So my next few trips will be all about finding what works, and what doesn’t. Wildlife photographs like we do can make these lens work hard so any ‘glitches’ should be obvious fast.

First an Anhinga hanging on a branch, over bright water. Shot at 600 mm.

Next, a bright white Ibis in the sun, with plenty of moving vegetation around. Shot at 450 mm. Not really pushed far.

Last, a young Great Blue Heron. The bird does not yet have any of the deeper blues or long breeding chest feathers. He looks pretty drab actually. Shot at 600 mm.
Not bad for the first hour of field use. Not heavy motion, but shutter was at 1/1200. Each image was cropped to a standard 8×10 print format.
Not seeing a distinct stabilization ‘lock’ is a little different. But weight and balance are very close to a Sigma 150-500.
They are one of my favorites, though I have only seen blues in the wild. I did have a large one fly close by while I was standing on a cliff. A comment everyone makes, but strikingly prehistoric.
They really are prehistoric. When the larger Great Blues land I call them ‘dragons’.