Tell the truth, I think fish eye looks bad for skate vids. So sick of it. I like wide and close but not so much barrel dist.
I've shot with the 6x and it's okay. But if you are buying I'd go with the 7x as it zooms all the way through. Which the 6x doesn't and makes me insane with rage.
Well, if you're going full on fisheye or "death lense" as skaters call it, go with a century optics .3x ultra fisheye. If you're going for less of a barrel distortion, but still want to go really wide, your next best bet is going to be the collinscraft .5x red eye. Do a search for it, you should find out what you need.