In the early days of digital SLRs, before the arrival of its smaller-format EF-S lenses, the 17-40mm was one of the mainstays of the Canon range, a super-wideangle zoom for the full-frame EOS 1Ds but also the nearest thing at the time to a ‘standard’ zoom for the newer, smaller-format EOS models like the D60.

It’s been around a while, then, but the arrival of cheaper full-frame Canons has made the 17-40mm interesting all over again, especially since the 21-megapixel EOS 5D Mk II now brings professional-quality imaging down to a (sort of) affordable level. Indeed, this is the camera we’ve chosen to test the venerable 17-40mm with to see if it’s still got what it takes.

While the price might seem steep, it does actually represent pretty good value. Any 17-40mm zoom is a pretty exotic and therefore expensive beast – remember, this is a ‘real’ 17-40mm and not a ‘digital’ lens where you have to apply a focal factor to work out the equivalent focal length. Zooms don’t come much wider than this, and although Nikon has a full-frame 14-24mm lens, it’s almost twice the price of this one.

The initial signs are good. The EOS 5D Mk II itself is capable of astonishing resolution and clarity of detail, and this lens appears able to come close to the limits of the 5D Mk II’s sensor, which is no mean achievement for a lens which is several years old. As we found in our test of the Canon EF 24mm f1.4 lens, we’ve had to move the scale on our resolution chart to accommodate the figures generated.

However, other users have remarked that the 17-40mm’s edge definition is disappointing, and this is borne out in our tests, lowering the overall figures. The centre definition is quite exceptional, but resolution drops off considerably towards the edges of the frame and you really need to stop down to around f8 before they start to catch up. The softer edges are especially noticeable at the shortest and longest focal lengths.

That is a disappointment. If you routinely shoot outdoors or on a tripod, where smaller apertures will be the norm, you won’t find much to complain about, but if you want to exploit this lens’s constant f4 maximum aperture, it’s something to be aware of.

This lens does have other good qualities, though. It’s quite compact, and the zoom and focus movements are both light and smooth. By comparison, Nikon’s 14-24mm f2.8, say, is a monster. Canon’s USM autofocus motors are as quiet here as they are on later lenses, and it’s a pretty sweet-handling lens all round.

It’s not the only full-frame super-wideangle zoom in the Canon range. There’s also the 16-35mm f2.8L USM II, but this has a list price of £1,690, which is practically twice that of the 17-40mm.

As long as you make some allowances for its mediocre edge performance at wide apertures, then, the 17-40mm f4L USM offers by far the cheapest way to discover the extraordinary visual effects of super-wideangle photography on a full-frame EOS body.

Not only that, here is a lens which can be used either on an EF-S format Canon or a full-frame model. What’s especially significant at this time is that full-frame lenses like this are an ideal investment for Canon users on the cusp of moving into full-frame.

Final Verdict The Canon 17-40mm’s optical performance might have its weak spots, but for a super-wideangle full-frame lens it’s good value OVERALL

Our lens reviewer, and technical expert, Rod is a veritable photographic encyclopaedia. His illustrious CV has seen him write for many mags, websites and journals.