exposure lock trouble
i've tried shooting movies in ma 550d,with 18-55 lens, but i have trouble when it come to locking the exposure,exposure varies while zooming in or out even after hitting the ' * ' button before taking a shoot.
Even after switching to manual mode for movie, when i zoom in or out the shutter and aperture varies( even after hitting the lock key ( * ) )
So what i get in a zooming shot is that it switches from bright to dark. what should i do to overcome this?