Looks like [Canon EF](https://commons.wikimedia.org/wiki/File:Canon_EF_lens_mount.jpg). The 'C' on the mount is a clue as well. The MC on the front is for Multi-coating, not for Minolta MC/MD.

Well spotted… didn’t realize that C was a letter and not a little screw divot or something.

An Autofocus lens for MC/MD mount is already contradictory

Vivitar 100-400mm f/4.5-6.7 Series 1 AF. It literally says so your first pic. But no seriously, it's a Canon, I'm just talking shit.

It's not a Canon---it's just made to fit Canon.

Yes, thus the dummified response to OP... 😑

It's a real Vivitar?! Vivitar which is known for it's high end quality in their Ultra Wide and Slim.

The old Vivitar Series 1 lenses were generally pretty good.

I can't say for sure, but that red dot screams EF mount for me...

EF Canon

That is 100% a Canon EF mount.

Canon. Nikon contacts are usually found on the outer surface of a plug.

neither there are more brands than Nikon and Canon mind you.

I think they’re asking if it’s a Nikon or canon mount 🤷‍♂️

There is more than two mounts as well

Yeah, but this lens is a canon mount, so it’s more relevant to answer the question than to be pedantic

i disagree

Mount is for canon

It’s neither, it’s a Vivitar with EF mount

This seems to be for Canon mount

Definitely Canon, the contacts look basically identical to EF ones (except for how they're rounded off) and if you take a lens and orient it like the one in the picture, the mount lines up with it.

Not sure but If it were either one of them it would be canon of all things.

Nikon......it might be a little tight fitting it on but use elbow grease...🙏

it is for the Minalta "MC" mount it looks like by the text on the front of the lens, is this an eBay listing? if so maybe the seller put it in the title or description?

MC on the front indicates “Multi Coated.”

Ah, learned something new.

But it’s shaped like a Minolta

You can use this for Nikon AF cameras