Hi A1ex, I think I just found the problem ! It seems that the cameras noise reduction interfers with AETTR. The 5D Mark II noise reduction starts at 1sec. Exactly the exposure where the zebras went wrong. I turnt off noise reduction and the camera is just exposing perfectly fine ! I will test it more intensely to confirm.
Now it seems logic to me: When noise reduction is on, the camera takes a second picture (dark) to reduce the noise. This second dark picture is immediately taken into account of ML's AETTR. And since its dark, AETTR switches to maximum exposure. If I had known about the operating of noise reduction I would never have had it activated !!
Now it seems logic to me: When noise reduction is on, the camera takes a second picture (dark) to reduce the noise. This second dark picture is immediately taken into account of ML's AETTR. And since its dark, AETTR switches to maximum exposure. If I had known about the operating of noise reduction I would never have had it activated !!