Canon EF 17-40mm f/4L USM Lens Review

 The Canon 17-40mm f/4L ultra wide angle zoom lens is an affordable, light, compact and high performance option for the photographer looking to make the most of wide angle photography applications. The 17-40mm f/4L is the smallest and lightest lens that features a Canon “L series” designation. As an “L series” lens, the optical quality is excellent.While used in a traditional landscape photography setting, the 17-40mm f/4L produces sharp images with lots of contrast.

Canon EF 17-40mm f/4L USM Lens

This lens in fact rivals the images produced by the most expensive 16-35mm f/2.8L lens. Additionally, this lens is weather sealed and sturdily built. In addition to a full time manual focusing mode, ultra quiet ring type USM powered autofocus provides fast and accurate focus operation. Finally, the 17-40mm f/4L is priced competitively making it attractive to high level amateur and professional photographers looking for an all around wide angle work horse lens that can handle a variety of shooting situations well. Photographers commonly use this lens for landscape photography, architectural photos and a variety of portraiture applications.

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