I feel stupid for asking this question. I see people talking about them all the time. I've even seen pictures of them.

What do they do?

In their simplest form, they act as a lens shade, keeping glare off the lens. Some will allow attachement of "flags" on the tops and sides, to extend this shading capablility. The good ones allow for "trays" that hold filters in front of the lens. (Polarizing filters, ProMist diffusion, graduated filters to name a few.) The better ones will have revolving or 'geared' trays that can rotate or elevate one or more filters.

The cheaper one will mount directly to the lens. The more expensive and complicated one will attach to the camera body/tripod with a system of rods that hold the matte box in place. Additionally, the rods can be used to mount focus pullers and zoom controllers that connect to the geared barrels of the lens.

Oh yeah, they make your camera look cool...

Hrmm. Thanks alot for the reply.

I guess I've never done any intensive outdoor shooting when it was very sunny so I've never really had any glare on the lens.

What does it mean when they are like 4x4 matte boxes and such?

4x4 is the size of the filter they hold.

http://www.cavision.com/Mattbox/4x4&Canon.htm

It's the big black doohickey on the front of the camera lens (in case you haven't seen one before)

Brandon,

Of course, glare from the sun outdoors is a big issue, but on a film set, quite often the lighting from different angles will also throw glare on the lens. If the light itself cannot be shaded, or a "Flag" set up on a stand nearby, to stop the flare, then the flags on the mattebox will do the trick.

Ok. I understand it now.

Nice to be finally figuring out all of these things I hear about, but don't understand.

Thanks alot for the help!

And by the way, the term "Matte Box" originated because in the old days, it was a structure that also held "mattes" in front of the lens. Think cardboard cut-outs in the shape of ovals, keyholes, binoculars... etc. (And yes, you can still put them in the filter holders!)

An' chicks dig 'em!