Reviews and Problems with Canon EF 17-40mm f/4L USM
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Canon EF 17-40mm f/4L USM lens, (tested with cropped-frame APS-C body)
1 July 2007
Summary: 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.
Pros: Canon 'L' build and optical quality, Fast and quiet USM focusing motor, Constant f4 aperture throughout range, Will also work on full-frame body
Cons: 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
Summary: Canon EF 17-40mm verdict
The EF 17-40mm f/4.0L is one of the best lenses in Canon’s range. It brings you a taste of the truly exotic with ultra-wide coverage, while boasting ‘L’ quality all at a surprisingly affordable price.
Pros: Extreme wide angle coverage, Well-corrected at wider focal lengths, Fast and quiet USM focusing motor, An exotic but affordable 'L' lens
Cons: Zoom range too limited for general purpose, Soft corners at 40mm focused at infinity, Unimpressive macro capabilities, Light fall-off at wide angle (but expected)
Canon EF 17-40mm f/4 USM L (full format) - Review / Test Report
26 September 2008
Conclusion: It's not exactly easy to design a flawless full format lens and the Canon EF 17-40mm f/4 USM L shows its part of the struggles here. The lens is not overly fast but it has a comparatively broad range for a lens in this class and it seems as if Canon has overstretched things a little with respect to...
Conclusion: The Canon EF 17-40mm f/4 USM L showed a very good to excellent performance in the lab as well as during the field tests. The lens exhibited very little vignetting and excellent resolution figures. On the downsode the level of distortions could haven been a little better at the wide-angle setting.
Conclusion: The Canon EF 17-40mm f/4 USM L is a very good performer without a significant weakness. It's generally very sharp and contrasty across the image field. Vignetting is very well controlled - at least when using it on an APS-C DSLR.