So I recently got the Rokinon 8mm f2.8 fisheye lens and it's a pretty fun lens to use. However, now I'm wondering if I should get a UWA lens instead since most of the time I would much rather have little to no distortion with the image. Think it's a good idea to get the 10-18mm lens instead? The 8mm is very sharp and at a very great price. At over $800 is the 10-18mm worth getting?