Hi, I recently got a Nikon D3300 second hand for mostly filming bands and occasionally skating, I was going to buy a fisheye for it to film some skating, I found a lens on EBay which is a The Kelda 8mm F3.5 Fisheye Lens, not expensive but isn’t a Nikon, the thing is it is Manual mode to use it, does this make rolling behind someone filming lines impossible? Will it go in and out of focus? Is it a waste of money, I’m not sure how it fulling works, can anyone help with SLR knowledge and video filming