Why are lens hoods used in cinema so large?

How come cinema cameras use large rectangular lens hoods? Are the equipment requirements in terms of optics for cinematography significantly different from stills photography?

I haven't been around many, but the impression I got was that they were designed to be adjustable so that you set the flaps to the lens and lighting you are using, rather than having a single small hood for each and every lens. Simpler and easier to build as a generic system in that fashion as well.

Large hoods also mean a large safety net against stray light striking the lens from odd angles.

Your thinking of a matte box. One of the reasons they're so large is because they use square filters (4x4), most cinema lenses also have a very large front diameter.

windlight wrote in post #15802206
How come cinema cameras use large rectangular lens hoods? Are the equipment requirements in terms of optics for cinematography significantly different from stills photography?

Terminology note: the devices are correctly called "matte boxes."

Filmmakers often use lights in front of the camera position, so they need larger boxes to prevent flare.

DC Fan wrote in post #15802273
Terminology note: the devices are correctly called "matte boxes."

Filmmakers often use lights in front of the camera position, so they need larger boxes to prevent flare.

Ah ok.

DC Fan wrote in post #15802273
they need larger boxes to prevent flare.

Unless they're called J. J. Abrams

Or Michael Bay...

So yeah, a matte box works 3 functions:
1. Adjustable to any focal length lens
2. Filter holder
3. Doesn't need to be removed while changing lenses, as the matte box sits on rails under the lens, rather than being attached to the lens itself.

Every lens in a given set (super speeds, panchros, MP's, etc.) are all of identical size/diameter, which allows matte boxes to be practical as well, as one box can fit a whole set.

Basically, it's an all-in-one overkill piece of gear that the world of cinema can justify using, but would be woefully impractical for general video, let alone photography use.