Until now, the widest rectilinear lens available for a full frame DSLR was the variable aperture Sigma 12-24 f/4.5-5.6. Nikon has the excellent 14-24mm f/2.8, but that suffers from enough rectilinear distortion to knock its practical focal length to something closer to 15+mm once it is corrected. The Canon 11-24 did not appear to have any rectilinear distortion that I could see.
Yes, it is f/4 vs f/2.8 for the Nikon lens, but making an element for an 11mm focal length accommodate an f/2.8 aperture would have boosted the already heavy 2.6lb lens even more. I actually sold off my Nikon 14-24mm because of its weight and size.
This is the perfect lens for dramatic landscape and architectural photographs. A lens this wide is quite specialized and is not for everyone, but, if it suits your shooting style, you're going to be as excited by it as I am. Added to the newly announced 50mp Canon camera coming out later this year, this will make a perfect landscape kit.
At $2999 this lens is definitely only for photographs with a serious need for such a wide angle. When this lens is more readily available I may be tempted to run it through its paces for a hands-on blog review.
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