The sigma 15mm f28 ex dg diagonal fisheye lens sigma fit is a full frame fisheye auto focus lens that fills the entire 35mm negative with a full 180 degree diagonal field of view this unique lens enables you to create a variety of unusual compositions even when shooting ordinary subjects the improved dg lens coating reduces flare and ghosting which is a common problem of digital cameras and also creates an optimum colour balance since most digital slr cameras use a smaller image sensor si