If you’re not planning on following the full frame Canon EOS 5D or Canon EOS 1Ds route quite yet, but still want an extreme wide angle, then this is Canon’s answer. Although it’s significantly cheaper than the Nikon 12-24 DX, the lens feels well made and all controls operate smoothly. Fit and finish are in a different league from the cheap plastic of the Canon 18-55 EF-S. In 35mm or full frame digital terms this lens is equivalent to a 16-35mm lens which is great - I’ve missed really wide angle lenses since I went digital. Incidentally Canon EF-S lenses can only be used on the Canon APS-C DSLRs from the 20D / 300D / Digital Rebel on. They can not be used on any film or full frame Canon DSLRs. EF-S lenses are mounted by aligning a white marker, rather than the usual red, so to check compatibility, look for a white dot on your camera’s lens mount just round from the red lens mounting dot.

Performance is better than I’d expect from such an extreme lens - no disastrous fall off in sharpness or illumination in the corners at full aperture. OK there is a little but not much. Stopped down to f 5.6 very fine detail is recorded everywhere except the extreme corners. Distortion, although present is also lower than expected and correction is readily available from both PTlens and DxO.  So far I’m impressed with the Canon 10-22 EFS - My only complaint is that at this price level the hood shouldn’t be a £ 30 extra.

Canon 18-55mm EF-S at 18mm

The second frame below was taken from the same spot but with the Canon 10-22 EF-S at 10mm - about 16mm in film or full frame terms. Changes in focal length of only a few millimeters make a much bigger difference with wide angle lenses than with telephotos where an 8mm difference would be barely noticeable.

Canon 10-22mm EF-S at 10mm

Seriously wide.