Thanks DoomMeister,
ok, i have try in 4 modes : ISO manual + shutter manual - ISO manual + Shutter auto - ISO auto + Shutter manual and ISO auto + Shutter auto
in this 4 modes all the time the 3 pictures are same exposed , no bracketing !! (no change on exif) in +/-0.3 or 0.7 EV
i really don't...