- Nikon 24mm f/1.4G ED ($1,999.95, released in 2010)
- Sigma 24mm f/1.4 DG HSM Art ($849, released in 2015)
- Canon 24mm f/1.4L II USM ($1,649, released in 2008)
I used Sigma’s geometrical (theoretical) chart, since Canon and Nikon themselves only show theoretical measurements (the differences with the diffraction chart are almost nil anyway). I tried to make the comparison easy by making the charts roughly the same shape and size, and removing distractions, including Canon’s measurements at f/8.
So this reveals basic lens performance (contrast and resolution), as well as optical issues such as field curvature and astigmatism. To make it simple, the top pair of lines represents the contrast, and the lower lines show the resolution – from the center (0 mm) to the full-frame corners* (21.6 mm). Higher is better.
The Sigma 24mm f/1.4 DG HSM Art is ahead by some margin here. It appears to be consistently sharper and more contrasty than its two rivals, with the Canon faring the worst. See the lines curving up and down? This is pronounced field curvature – a scourge when shooting distant scenes.
Even with the usual sample variance (not all lenses can be created equal), the extra pop and bite of the 24mm Art wide open seem significant enough to be noticeable in any well-made, real-world comparison between the Sigma lens and its competitors.
Let’s recall that MTF charts don’t tell the whole “image quality” story though. Distortion, coma, flare, chromatic aberration, bokeh, sharp/unsharp transitions… are aspects of image quality that matter to anyone after a super-fast 24mm prime lens, but can’t be assessed here.
Okay, I see you like MTF charts nonetheless, so have a look at how the new Sigma 24mm f/1.4 Art compares to the discontinued 24mm f/1.8 EX.
At f/1.4, the 24mm Art bests its older sibling at its widest aperture of f/1.8. Of course, the Art lens must be given extra credit in this match, as the performance shown here is achieved at a more extreme aperture setting (f/1.4 vs f/1.8). It’s supposed to be even better when stopped down to f/1.8.
* With Canon’s APS-C sensors (1.6× crop), the far corners are at 13.4 mm from the center. With 1.5× APS-C sensors, the far corners are at 14.2 mm from the center.