Whatever you get, try to get something with little to non vignetting. I want to puke every time i see some edit of a follow cam and there is a circle within what should be a square shot. I'd rather have a close tight shot or a distant tripod shot ANY day. Wide angle lense will more than likely have less vignetting than a fisheye. And spend money on it, a cheap lens is a shitty lens, so don't be afraid to drop some cash on it, it will be worth it.