Canon EF 17-40mm f/4L USM lens (full-frame tests)
-
-
Written by Gordon Laing
Canon EF 17-40mm f/4L USM wide-angle uniformity using Canon EOS 5D
Canon 17-40mm results: Outdoor / Resolution / Corner sharpness / Fringe and macro / Geometry / Vignetting
Canon 17-40mm results
Outdoor / Resolution / Corner sharpness / Fringe and macro / Geometry / Vignetting
|
To measure lens vignetting and light fall-off we photographed a white target with a highly diffused custom filter. The lenses were tested at their widest focal lengths with the aperture wide open using a Canon EOS-5D in Aperture Priority mode. The images were analysed with Imatest and the full areas presented here at a reduced resolution. Bigger percentages are better. All three lenses performed similarly here, with light falling off by almost two thirds by the time it reached the corners. Light fall-off is always a problem with wide-angle lenses, but particularly so for those which have to perform for a full-frame sensor or 35mm film. Full frame sensors further accentuate the problem because with wide angle lenses, the light rays are striking the sensor’s micro-lenses towards the corners at a shallower angle, effectively rendering them less sensitive. |
Canon EF 17-40mm f/4.0L USM |
Canon EF 24-105mm f/4L IS USM |
Canon EF 24-70mm f/2.8L USM | ||
 |  |  | ||
|
17-40mm at 17mm f4 Mean corner fall-off: 34.3% |
24-105mm at 24mm f4 Mean corner fall-off: 33.3% |
24-70mm at 24mm f2.8 Mean corner fall-off: 34.1% |
Canon EF 17-40mm f/4L USM telephoto uniformity using Canon EOS 5D
|
To measure lens vignetting and light fall-off we photographed a white target with a highly diffused custom filter. The lenses were tested at their longest focal lengths with the aperture wide open using a Canon EOS-5D in Aperture Priority mode. The images were analysed with Imatest and the full areas presented here at a reduced resolution. Bigger percentages are better. Once again, the full-frame coverage presents a challenge to any lens, with all three scoring lower than many equivalent focal length lenses would on cropped bodies. That said, the 17-40mm delivers the best result here with relatively little fall-off compared to the others. |
Canon EF 17-40mm f/4.0L USM |
Canon EF 24-105mm f/4L IS USM |
Canon EF 24-70mm f/2.8L USM | ||
 |  |  | ||
|
17-40mm at 40mm f4 Mean corner fall-off: 63.1% |
24-105mm at 105mm f4 Mean corner fall-off: 54.5% |
24-70mm at 70mm f2.8 Mean corner fall-off: 52% |
