To compare the corner sharpness of the Canon 350D / XT with the EF-S 17-85mm against the Canon 5D with the EF 24-105mm, we photographed the Enhanced Digital Camera
Resolution Chart with each lens at their widest and longest focal lengths and
various apertures in Aperture Priority mode.
The EOS 350D / XT and EOS 5D were set to their
best quality JPEG and default image tone and sharpening settings. The crops are taken from
the extreme lower left corner of the chart and presented here at 100%.
The Canon EF-S 17-85mm clearly exhibits greater geometric distortion and coloured fringing than the EF 24-105mm when both lenses are zoomed-out to their widest positions. Stopping down the former improves the sharpness slightly, but the colour remains.
Zoom both lenses into telephoto though and the story changes. Here the EF-S 17-85mm delivers much sharper results in the far corners than the EF 24-105mm; indeed the latter is quite soft in the corners even at f8.
Note: crop details taken from the same chart which appear smaller here are
due to them being captured with lower resolution cameras and / or a lens
which couldn't focus as close to the chart. In each case though, the crop
still represents the extreme left corner of each camera's frame. |
