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Canon TS-E 17mm f/4 L - Analysis - conventional setup |
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Lens Reviews -
Canon EOS (Full Format)
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Page 3 of 4
Let's begin with our technical analysis based on lens in its conventional setup with both the tilt as well as the shift aspect in their respective neutral settings.
Distortion
Ultra-wide lenses tend to be a bit "laissez-faire" when it comes to distortion but the Canon TS-E 17mm f/4 L plays in a different league here. It shows only slight barrel barrel distortion of just over 1.1% albeit based on a somewhat wavy subfrequency. This is highly impressive for a lens in this class.
The chart above has a real-world size of about 120x80cm.
Vignetting
The Canon lens has an immense image circle so it's no surprise that its vignetting figures are about as good as it gets today. Technically the vignetting is naturally still fairly pronounced at f/4 (@ ~1.3EV) but this is very acceptable for an ultra-wide lens - the Canon EF 16-35mm f/2.8 is worse @ f/4 for instance.
MTF (resolution)
The resolution characteristic of the Canon lens is impressive. The center resolution is already excellent at max. aperture whereas the borders/corners are on a good level. Stopping down to f/5.6 and f/8 boosts the borders well into very good territories and the extreme corners follow closely. Diffraction effects decrease the quality a little at f/11. At f/16 the quality is still good to very good across the image frame.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness.
If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Canon claims to have optimized to the lens with respect to lateral CAs and our findings to support this statement. An average CA width of around 1px at the image borders is very good in absolute terms and even more so for an ultra-wide lens.
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