|
Canon EF-S 17-85mm uniformity, wide angle
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 length with the aperture wide open using a Canon EOS-350D /
Digital Rebel XT in Aperture Priority mode. The images were analysed with
Imatest and the full areas presented here at a reduced resolution.
With light falling off to an average of 57.8% in the corners, the 17-85mm
EF-S was noticeably worse than the other two lenses. The light fall-off
at wide angle is probably the worst aspect of this lens and is quite visible
in some of our gallery shots on the previous page. The 17-40mm EF L, designed
for a full frame camera, unsurprisingly performed best in this test, although
light fall-off was still measured at 79.4% even in the corners of the cropped
frame of the 350D / Digital Rebel XT. |
Canon EF-S 17-85mm f4~5.6 IS USM |
|
Canon EF-S 18-55mm f3.5~5.6 |
|
Canon EF 17-40mm f4.0L USM |
|
|
|
|
|
17-85mm EF-S at 17mm f4
Mean corner fall-off: 57.8% |
|
18-55mm EF-S at 18mm f3.5
Mean corner fall-off: 68.8% |
|
17-40mm EF L at 17mm f4
Mean corner fall-off: 79.4% |
Canon EF-S 17-85mm uniformity, telephoto
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 length with the aperture wide open using a Canon EOS-350D
/ Digital Rebel XT in Aperture Priority mode. The images were analysed with
Imatest and the full areas presented here at a reduced resolution.
Zoomed-in to their longest focal lengths, all three lenses performed quite
similarly and while the 17-85mm EF-S was still the worst of the group, it
almost caught up with its rivals. Interestingly though, despite being designed
for a full-frame body, the 17-40mm EF-L performed no better than the budget
18-55mm EF-S in this test even on a cropped body. Indeed the 18-55mm EF-S
scored fractionally higher, although the difference wouldn't be noticeable
in real-life. |
Canon EF-S 17-85mm f4~5.6 IS USM |
|
Canon EF-S 18-55mm f3.5~5.6 |
|
Canon EF 17-40mm f4.0L USM |
|
|
|
|
|
17-85mm EF-S at 85mm f5.6
Mean corner fall-off: 77.5% |
|
18-55mm EF-S at 55mm f5.6
Mean corner fall-off: 83.8% |
|
17-40mm EF L at 40mm f4
Mean corner fall-off: 82.2% |
|
