Canon EF 17-40 mm f/4.0L USM
- very good picture resolution in the center and at the edge of the frame
- very well controlled chromatic aberration
- low distortion
- well controlled coma
- low astigmatism
- very small vignetting
- good work in bright light
- quiet and fast autofocus
- high quality build
- reasonable price
- USM motor autofocus could make less mistakes
- We expect better resolution from the L-grade lens
When reading each part of the test carefully anyone will come to the conclusion that it is hard to say anything negative about the Canon 17-40 mm. Even the cons that we enumerate in the summary are minor.
The strongest competitors for the tested Canon would be the Canon 17-55 IS USM and Tamron 17-50 f/2.8. They are both better than the Canon as far as picture resolution, focal length ranges, stabilization and aperture are concerned. In the other parameters, however, the L-grade Canon is better, correcting the off axis optical distortions and smaller vignetting, plus having a more solid build. It is worth adding that all three lenses differ from each other as far as price is concerned. In this category the winner would be the Tamron, which costs 1,000 Polish zloty less than the Canon. On the other hand, it is the weak point of the Canon 17-55 mm IS USM because we can ask the question whether it is worth spending more than 2,000 Polish zloty to get the L-grade Canon, yet only gain slightly better resolution and stabilization.
We have to remember that the Canon 17-40 mm is a lens designed for full frame. It is a big advantage. When you buy the lens, you buy it for years. First of all, the build quality ensures long lasting operation without any problems. Secondly, in a few years, when the APS-C detector cameras will disappear from the market, our Canon 17-40 mm will still be of great use, not as a kit lens any more but as a great ultra-wide-angle lens for landscape photography and journalism.
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