Samyang 14mm f/2.8 IF ED UMC Aspherical - APS-C Review / Test Report - Analysis
Lens Reviews -
Canon EOS (APS-C)
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Ultra wide angle lenses often struggle to tame the amount of barrel distortion and this is also a major weakness of the Samyang 14mm f/2.8. It produces a whopping 5% barrel distortion. For serious architecture photography this is pretty much a no-go unless you correct the problem during post-processing. The barrel distortion isn't quite as complex as on full format DSLRs fortunately.
Note: the chart above has a real-world size of about 120x80cm.
Vignetting is another critical aspect for ultra-wides especially on full format DSLRs. The Samyang shows a very pronounced light-falloff at f/2.8 - more than 1.3EV/f-stops. Stopping down to f/4 resolves most of the issue and it's not overly relevant anymore from f/5.6 onwards.
As already mentioned the Samyang is already capable of producing impressive results on full format cameras and the show goes on here as well.
The Samyang produced nothing short of outstanding resolution figures for a lens in this class. The results are very even across the tested aperture range which means excellent to superb center resolution and very good to excellent borders. Field curvature (flatness of the focus plane) is well controlled.
I reckon that you will not believe us so please have a look at our field image section.
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
Lateral Chromatic Aberrations (CAs)
The CA characteristic (color shadows at harsh contrast transitions) are also very well corrected at less than 1px at the image borders. This isn't overly field relevant but somewhat more pronounced than what we've seen in the full format tests.