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When bought for a cropped-frame body Good points Canon ‘L’ build and optical quality Fast and quiet USM focusing motor Constant f4 aperture throughout range Will also work on full-frame body Bad points Shorter zoom range than kit lens No IS (although not particularly necessary) Overkill if not considering full-frame in future Canon EF-S 17-85mm more flexible for most Scores (relative to 18-55mm kit lens)   Build quality: Optical quality: Specification: Value: Overall: 22 / 25 21 / 25 18 / 25 16 / 25 77%

The Canon EF 17-40mm may deliver spectacular ultra-wide angle coverage when fitted to a full-frame body like the EOS 5D, but offers a more normal, general-purpose range when mounted on cropped bodies like the EOS 30D or 400D / XTi. As such when evaluating it for cropped bodies, it’s important to compare it against other general purpose options like Canon’s standard kit lens and the popular EF-S 17-85mm.

At first glance the EF 17-40mm comes up short compared to the other general-purpose lens options for cropped bodies – literally. With a focal range of 17-40mm, it may zoom fractionally wider than the kit lens, but doesn’t get as close. This difference is even more apparent compared against the EF-S 17-85mm, which zooms-in more than twice as far, and boasts Image Stabilisation, all for slightly less than the asking price of the EF 17-40mm. So when you look at it like that, the EF-S 17-85mm is a far more flexible option for owners of EF-S compatible bodies.

But the EF 17-40mm has several unique advantages. First of all, it’s an ‘L’ lens, which means superior build and optical quality. The former is really noticeable too when you compare them side-by-side with EF-S models. The ‘L’ lenses feel tougher and feature much smoother manual focusing and zoom rings; the ‘L’ zoom rings feel like you can turn them as finely as required, whereas the EF-S zoom rings seem to almost catch in comparison.

Another benefit of ‘L’ lenses is they come with lens hoods (and pouches), unlike the rest of Canon’s lens range where they’re unforgivably an optional accessory. The EF 17-40mm also features a constant f4.0 aperture throughout its range.

In terms of optical performance, the EF 17-40mm matches the EF-S 17-85mm by getting the highest resolution from the best cropped-frame bodies so far, while also delivering sharp, high contrast results with minimal colour fringing. The corner sharpness, geometric distortion and light fall-off results on a cropped body are also very respectable.

The optical results shouldn’t come as a surprise as the EF 17-40mm’s trump card is its ability to also work on a full-frame body. So when fitted on a cropped-frame body like the EOS 30D or 400D / XTi, you’re actually avoiding the outer areas of the optics which don’t perform as well. This compatibility with full-frame bodies also gives the EF 17-40mm an upgrade path which isn’t possible with any of the EF-S lenses.

So buying the EF 17-40mm for a cropped-frame body gives you great optical performance, fast and quiet USM internal focusing, a constant f4 aperture, ‘L’ build quality, a lens hood and the opportunity to re-use it on a full-frame body should you upgrade in the future. On the downside, the focal range is actually lower than the kit lens and it’s missing the Image Stabilisation of the other upgrades.

Ultimately while the EF 17-40mm represents great value for an ‘L’ lens, its shorter focal range means it’s not a practical single lens upgrade for owners of cropped-frame bodies; unless you’re exclusively into wide angle work, you’ll inevitably find the 40mm focal length just comes up too short for a single lens solution.

Consequently we can only recommend it to cropped-frame body owners who have at least one other lens to cover longer focal lengths, and who are also seriously considering a full-frame body in the future. For these people, the EF 17-40mm is a great choice, although most others will find models like the EF-S 17-85mm more flexible as a general-purpose all-round lens. To see the EF 17-40mm in action on an EOS 400D / XTi body, check out our Canon 17-40mm video tour.

Note: If you own the EF-S 18-55mm kit lens and are wondering what benefits there are to upgrading, check out our Canon kit lens upgrade group test. This compares the EF-S 18-55mm against the EF-S 17-85mm, EF-S 17-55mm and the EF 17-40mm lenses.