What would you call this part and where could I order a new one?

This goes below the focusing screen on my 6D and appears to be a clear piece of plastic. I thought I had a fine hair in there but it appears to be an imperfection with this plastic. Takes about 10 seconds to replace so figured I'd just do it myself since there is no canon service center anywhere here

That piece of plastic IS your focusing screen. The 6D has three screens available, which are described in the manual, custom function C.Fn III -2 (page 312 of the English language one).

Be careful, those screens are delicate, scratch and damage easily.

Google tells us that Amazon and bhphoto sell screens, though I haven't checked if they're 6D ones (like raw, each Canon seems to have its own screens).

gotcha, OK thanks so much! Need some plastic tweezers

Canon_Shoe wrote in post #17698395
gotcha, OK thanks so much! Need some plastic tweezers

The focus screens should NEVER be touched by your fingers. A new one comes in a plastic case with its own specialized hooked tweezers which attach to the tab shown on the upper right side of your photo. I sure hope you haven't be shoving your fingers in there. You could compromise both the mirror and the sensor if you don't know what your doing. Please be more careful. A replacement screen will cost around $35 to $40.There are usually 3 different types, the standard, the gridlines, and the super matte for manually focusing fast lenses. If you change the model of focus screen you use you also have to change a custom function setting to match it.

Thanks, ya this one is scratched I guess......I clean the sensor and everything myself, never had an issue of any kind with any camera body really.

Does the scratch really bother you?
I had a tiny spider on the focus screen of my 1D4, quite enjoyed watching them going about their business. Then the spider went away - I miss it now........
Unfortunately when I upgraded my new camera came without spiders = optional extra?

Bahahaha!!!!

B&H has them for the 6D for around $35, depending on which one you want. They're simple to replace, I did it when I had a 1DMkIII, but I wouldn't touch mine without the little tool that comes with them.

Cool, I got one coming for it

Is the mark effecting the autofocus?

No, just cosmetic......I already replaced it myself. Took about 30 seconds

I have a small black mark on both my 5D2 and 1DIV that can't be reached by blower, I know me well enough and I'm sure many are the same, but it bugs the heck out of me seeing it, even if it has zero effect on the images. Just a nuisance.

You just have to take out the focusing screen, and then those two little screws above it, then blow it out in there. Probably wouldn't do it by yourself if you don't feel comfortable in there

I can do it, just know that they don't show up is ok for now, I'm sure the itch will come when it needs scratched though.

Canon_Shoe wrote in post #17709939
You just have to take out the focusing screen, and then those two little screws above it, then blow it out in there. Probably wouldn't do it by yourself if you don't feel comfortable in there

You don't need to remove any screws to replace the focus screens on the 6D and 5DII, and from what I've read, in the 1D IV as well. What screws did you remove, and why do you think you needed to remove them?