By 14mm, the Sigma is already at f5.0 wide open (not the brightest of viewfinders to work with, therefore), so I’ve chosen f5.6 as the next comparison which of course handicaps the zoom somewhat. Not to worry: it will get its revenge at f16.
|Canon 14mm at f5.6 (centre)||Sigma 12-24mm at f5.6 (centre)||Nikon 14mm at f2.8 (centre)|
Before you leap to the conclusion that the Nikon is a total waste of space, check this edge crop:
|Canon 14mm at f5.6 (edge)||Sigma 12-24mm at f5.6 (edge)||Nikon 14mm at f2.8 (edge)|
Out in its annular sweet spot/ring/whatever, the Nikon is actually pretty great. And for all those ultrawide subjects where you need a soft centre frame surrounded by a hyper-crisp ring of resolution, this might be an ideal lens. You know, subjects like – uh… well… you know: there must be something this lens is good for? How about a paperweight?
|Canon 14mm at f5.6 (corner)||Sigma 12-24mm at f5.6 (corner)||Nikon 14mm at f2.8 (corner)|
What I’ve overlooked in all the excitement and confusion is that the Sigma is already matching the Canon 14mm centre frame – even at this aperture. However the Canon is pulling a lot more detail from the scene in the corners – but bear in mind that we’re comparing a prime two stops down with a zoom only half a stop from wide open. I’m impressed. We’ll consider distortion and CA later, but amazingly the Sigma renders ruler straight horizontals and verticals even in the extreme corner. And how many lenses at even twice this focal length are capable of that?
The less said about the Nikon the better. It’s some small consolation that the Nikon’s centre frame ‘sour spot’ has noticeably shrunk going from f2.8 to f5.6 – by it needs f11 to disappear entirely.