Sigma isn’t short of fast primes in its lineup, so where does this latest addition fit in? Michael Topham takes a closer look
Sigma 40mm f/1.4 DG HSM Art review: Image Quality
When we visited Photokina and inspected the lens for the first time we were told it’s one of the sharpest primes Sigma has ever made. To find out if this claim is true, our Canon-fit sample was coupled to the Canon EOS 5DS R and run through the lab before a series of comparisons were made against the company’s 35mm f/1.4 Art and 50mm f/1.4 Art lenses.
Our Applied Imaging tests tell us the lens resolves a good level of sharpness in the centre when it’s used wide open at f/1.4, which is clear to see in the real-world sample images that support this review. The centre and corners get much sharper by stopping the aperture down, with the sweet spot of sharpness at the centre and edge being located around f/5.6. Strong results are also obtained at f/8 and f/11.
Although it’s difficult to spot an obvious difference in sharpness between this lens and the Sigma 35mm f/1.4 DG HSM Art and Sigma 50mm f/1.4 DG HSM Art when it’s used wide open at f/1.4, you can make out that it is slightly sharper between f/2 and f/5.6 when fine detail is inspected at very close magnification. What’s more noticeable is how well the lens controls chromatic aberration. Whereas I’m used to having to correct for some green and purple fringes of colour in shots taken with the Sigma 35mm f/1.4 DG HSM Art and Sigma 50mm f/1.4 DG HSM Art, chromatic aberrations are superbly controlled and almost completely absent.
As for vignetting, corners to images taken at f/1.4 appear approximately 1.5EV darker than the centre, improving to 0.7EV at f/2. Stop the lens down to f/2.8 and shading is only traced at the very far corners. Some photographers will find the vignetting the lens creates at f/1.4 tasteful, and rather than have it corrected in-camera or remove it later, opt to keep it to draw viewers eyes towards the heart of the frame.
Distortion is another area where this lens excels and with a distortion figure of -0.4%, users can be confident that any lines towards the edges of the frame will be rendered straight and true.