Canon EF 17-40mm f/4L Test for Sharpness in Images
Comparisons
at 20mm with EF 20mm f/2.8 and with Sigma 20mm f/1.8 EX
Also, 20mm equivalent taken with EOS 20D and EF-S 10-22mm lens
Images were taken on the same day at f/11 aperture priority and at ISO 100 in RAW mode and automatic white balance. RAW files were converted to 300 dpi tifs with Capture One Pro v. 3.6. The tifs were enlarged in Photoshop 7 to 20 inch wide tifs, sampled and samples converted to 72 dpi jpg's. Sharpening and unsharp mask was used to optimize image sharpness.
Note: Test photos taken during variably breezy morning. Don't pay too much attention to leaves and and very light foliage that is moving in the breeze.
20mm or Equivalent
| Camera / Lens | Full Frame - 20mm or 20mm equivalent | Crop 1 - Left Edge | Crop 2 - Right Edge | Crop 3 - Center |
| EOS-1Ds EF 17-40mm f/4 @ 21mm & f/11 |
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| EOS-1Ds EF 20mm f/2.8 @ f/11 |
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| EOS-1Ds Sigma 20mm f/1.8 @ f/11 |
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| EOS 20D EF-S 10-22mm @ 12mm f/11 |
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