Is this CA?

Look at the helmut.

Is that CA?

If so, it is the first time I've seen it in practice.

From a 30D, 70-200 f/2.8 L IS + Cannon 1.4x TC.

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I think so, no idea about cause. Usually happy when there's HEAPS of light around i've found.

No sign of it from the 100-400.........

Pretty harsh light that day, too.

it's either CA from the lens + the tc or it's bloom on the sensor. i'd be willing to bet it's CA since you're using a tc.

If it were CA, you would expect to see red on the other side of the helmet. It looks more like sunlight glint off the helmet and probably some flare in the lens. You would also expect to see CA anywhere there is a significant contrast boundary such as around the edges of a black object. Also, you may just be seeing a JPG artifact.

Zoom in on the letters on the helmet or the lettering on the shirt to see if there is color fringing.

It's CA.

I think I see a bit of green as well, but more magenta. I'd say CA and blooming?

Thx gang. I'll check it out more closely.