About the Canon 8-15mm F/4L
The Canon 8-15mm F/4 lens is a unique fisheye lens from Canon that a lot of people enjoy using however its a very niche lens. When using this lens on a full frame at 8mm you can expect to have a circular image surrounded by a black frame. This is quite typical when using fisheye lenses and especially when using a short focal length such as an 8mm lens. This lens is compatible with all Canon EOS cameras as well. So if you are shooting with a crop sensor camera such as a Rebel or Canon 1D MKIV then you have no worries on whether or not this will work for you.