I am contemplating a wide angle lens for my 5D mk II. I am struggling between the 14mm L II and the 8-15mm L. Chances are excellent that I will not be purchasing another wide angle lens for along time. Currently on the wide end, I have a 17-40 L and a 24-70 L. I have no experience with either of the lenses I am inquiring about. The lens will be primarly used for landscapes and maybe some portrait shots to get separation and include cool backgrounds. My photography is primarily nature and wildlife, and I am only an amateur photographer.
The 14mm is an ultra-wide lens that is corrected for distortion. However, the 8-15 is a FISHEYE lens, which will give the image a round, distorted look.
By what you're going to be using the lens for, the 14mm would be the way to go.
If you scroll down to the comparison photos, there's one of the 14mm 2.8 lens. Notice the lack of distortion from the 14mm compared to the fisheye images (both from the 8-15 and the 15mm fisheye). Even at 15mm on a FF (and a crop camera) the lines are still very much barrel distorted inherent to the nature of the fisheye lens.
If the fisheye curvy look is what your going going for, then by all means get the fisheye. But, particularly on the 5D2, the 8mm range on the 8-15 is a perfectly circular image. That's a pretty stark/limited use type shot. Lot of money to spend on a lens of that nature for the limited use, I personally would get out of it. YMMV.
