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Canon EF 17-40mm f/4L USM Lens |
Canon 17-40mm F/4.0L Features
- Ultra wide angle zoom lens
- Focal length : 17-40mm
- Maximum aperture : f/4
- Filter Size : 77mm
- Optics : 12 Elements in 9 Groups Canon Micro UltraSonic Motor (USM) provides fast and accurate focusing.
- Weight : 500g
- Canon EF Mount
What Users Like About This Lens
The Canon EF 17-40mm f/4L ultra wide angle zoom lens receives praise for its excellent flare resistance, ability to create top-notch out of focus blur effects and excellent optical quality. This lens is not as fast as the higher priced 16-35mm f/2.8, but at medium apertures the two lenses are very comparable in terms of image quality. Perhaps the greatest asset of the 17-40mm f/4L is its price. This lens is very affordable and of very high quality, which makes it one of the most popular “L series” lenses in Canon’s lineup.
What Users Don’t Like About This Lens
Professionals have noted that the corners of images from the 17-40mm f/4L tend to lack sharpness. This problem normally occurs at the fastest apertures and diminishes as the aperture gets smaller. At f/8, f/11 and above images tend to have excellent sharpness from corner to corner. These results are acceptable as many use this lens at smaller apertures when working in landscape applications.
Additionally, vignetting is very prominent on full frame digital SLRs at f/4 and the 17mm focal length. Vignetting effects decrease at f/4 and 40mm, but are still noticeable. The 17-40mm f/4L is best used, therefore, on a 1.6x field of view crop factor digital SLR.
Source : http://www.digitalphotographygear.com