Whats with the huge Lens hood on Pro Video Cams ?

[marcwang]

I noticed pro video cams always have this huge lens hood, the square type. Surely it must be more than a lens hood, what is it for ?

 

[Bamboopictures]

If it has a filter tray and a french flag, it's safe to call it a matte box. Essentially it does what a lens hood does and holds two or more filters. You will definitely need ND filters if you want to stick religiously to 1/25 or 1/50 shutter speed and use shallow DOF.