Playing with some different settings...

[Didereaux]

Caught this Caspian Tern yesterday. Highly cropped as he was quite aways away. I was trying our some different settings for capturing flying birds with a Canon 7D(APS-C) and Sigma 150-600 C. This was done handheld in M(anual) mode 1/2000 F8 500mm(750 equiv) ISO AUTO(400). When the ISO is AUTO it adjusts even though you are in manual mode and that is the trick With these long lens's you must keep the shutter speed high, and Aperture closed down to capture with minimum blurring when shooting handheld. It seems to be working. Although you get the higher noise ISO's so far none so bad that they do not clean up in post.

straight out of camera no adjs.

..although this bird looks like he is just gliding along terns are constantly moving, dipping and diving like demented swallows most of the time.

 

[bulldurham]

Forster Terns move about the same way and they are fast little buggers too boot. I'm shooting full frame at 500mm and try to keep the shutter at 1/1600 if possible but I very rarely use auto ISO as it tends to go overboard and noise the heck out of shots that don't need it. Try Aperture Priority at wide open (I think that is 6.3 on that lens) since there is not much more you want in focus in the frame than the bird, and if you are lucky, a small fish. I shot the Sigma 150-600 Sport for a few weeks and while it was a sharp lens, it was just too dang heavy for an all day walk. My 200-500 is heavy enough.

 

[Didereaux]

Forster Terns move about the same way and they are fast little buggers too boot. I'm shooting full frame at 500mm and try to keep the shutter at 1/1600 if possible but I very rarely use auto ISO as it tends to go overboard and noise the heck out of shots that don't need it. Try Aperture Priority at wide open (I think that is 6.3 on that lens) since there is not much more you want in focus in the frame than the bird, and if you are lucky, a small fish. I shot the Sigma 150-600 Sport for a few weeks and while it was a sharp lens, it was just too dang heavy for an all day walk. My 200-500 is heavy enough.

What you describe and suggest is what my usual settings were. The problem I ran into with Ap mode is that your shutter speed changes, with T shutter mode then your DoF changes and with birds coming towards you you lose focus and auto focus on any camera cannot keep up with a fast bird. Works fine when you can pan, but at sharp angles toward or away auto focus fails. So hence my experimenting. As I said so far the noise issue has not been one and several times over thee past couple weeks it has been in the 1600-3200 range and cleaned up nicely. the following pic although not flying was shot with the 'flying' settings and the auto Iso went to 1600 with no ill effects.