Video with any OM-D or PEN

[BW79ST]

I haven't explored shooting video much to date, but I have run into a problem. How can I lock down the exposure values so that when moving into a temporary shaded area I still have the correct exposure when exiting into full sunlight? I always get a bloom that settles down in a second or so. The problem is pronounced when shooting from a vehicle and then going under an overpass. Coming out, the exposure values have changed for the dark area.

[RobertD]

Shoot using Manual mode.
Cheers, Rob