Sigma 105mm f/1.4 DG HSM review: Resolution, shading and curvilinear distortion
Resolution
The lens was coupled up to Canon’s 50-million-pixel EOS 5DS R before our Applied Imaging tests were carried out. Like Sigma’s 85mm f/1.4 Art lens, this optic manages to resolve a similar level of sharpness in the centre of the frame at f/1.4 as it does when it’s stopped down to f/11. Sharpness peaks in the centre at f/4 and to find the sweet spot between centre and edge sharpness you’ll want to use an aperture around f/5.6-f/8. The introduction of diffraction plays its part in softening images beyond f/11.
Shading
Uncorrected corner shading at f/1.4
Uncorrected corner shading at f/2.8
With such a large front element, the lens is able to deliver a significantly greater volume of peripheral light than other prime lenses. The result is an extremely impressive vignetting performance, with edges proving to be unnoticeably darker than the centre of the image, even at its maximum aperture of f/1.4. We measured the edge of images to be just 0.3EV darker than the centre of the frame at f/1.4.
Curvilinear Distortion
Uncorrected curvilinear distortion, 0.3% TV SMIA
Curvilinear distortion is rarely an issue on telephoto prime lenses. Users of the lens won’t have any concerns of barrel or pincushion distortion causing any issues and with an extremely low -0.3 distortion figure it sits among some of the best lenses we’ve tested. Our distortion chart above clearly shows that straight lines appear straight to the eye on both horizontal and vertical axis, just as they should.
