I’ve always shot with a circular fisheye on a cropped sensor DSLR, which results in black round corners, but this has never bothered me. On the few photos where this is a distraction I can cover them up with Photoshop, or crop them out. I look forward to experimenting with the lens on a full-frame sensor one day, when the whole circular image will appear in the frame.
It merely becomes a diagonal fisheye lens with reduced zoom range, and the heavily distorted fisheye effect is largely lost at the long end of the zoom range on an APS-C camera.
Here are fifteen examples of fisheye photos from my collection that show the versatility of the lens, and will hopefully inspire you to try one for yourself:
On a full-frame camera such as the , the EF 8-15mm Fisheye is a wonderfully versatile lens that enables you to switch between circular and diagonal fisheye effects with a twist of the zoom ring. Image quality is very good in terms of sharpness, contrast and resistance to ghosting and flare, although colour fringing can be quite noticeable.