I primarily used the 12mm 1.4 DC Contemporary with the EOS R50 V in the field, but switched to the 33MP EOS R7 for lab tests. The 12mm scores in the very good range on an Imatest SFRplus evaluation with the R7’s pixel-rich 33MP sensor, showing around 3,000-3,300 lines from f/1.4-11. There’s a noticeable drop off in picture quality at the minimum f/16 aperture; optical diffraction softens the output, and the lens scores in the low register for the sensor, around 2,400 lines. You may want to use the lens at its minimum aperture situationally, though, at f/16 it draws gorgeously crisp 18-point sunstars.
Canon EOS R50 V, f/16, 1/80-second, ISO 400 (Credit: Jim Fisher)
If you use your camera for JPGs or movies, you won’t have to worry about a distortion or vignette, both are corrected by your camera’s image processing system. Raw images aren’t processed in-camera, however, and optics show heavy barrel distortion at any f-stop and darkened corners when used at brighter settings (f/1.4-2). Thankfully, Adobe’s lens correction profile (LCP) system makes it pretty easy to fix images; it just takes one click to apply a profile in Lightroom Classic. Adobe has not yet released a profile for the 12mm F1.4, but Sigma provided me with an early copy for testing, and it works as expected. With some lenses, it’s okay to skip a profile, but the distortion from this one is heavy enough that you should make sure your photo editing software supports the feature before adding the 12mm F1.4 to your kit.
Canon EOS R50 V, f/1.4, 1/100-second, ISO 100 (Credit: Jim Fisher)
I’m happy with how well the 12mm F1.4 controls flare. I made several images into the sun and didn’t have to worry about a loss of contrast or false color. I noticed some large ghosts (false color caused by an internal reflection) in one backlit scene with the sun positioned just at the top of the frame, but since I was using a neutral density filter, I can’t directly attribute it to the lens, but I couldn’t reproduce the effect making photos directly into the sun without a filter at any aperture.
Canon EOS R50 V, f/4, 1/2-second, ISO 100 (Credit: Jim Fisher)
You won’t get blurred-out backgrounds in every situation with this lens. Even though the aperture opens to f/1.4, the 12mm focal length simply doesn’t provide enough compression for the effect when taking photos with a distant focus point. But if you’re able to get within a couple of feet of your subject and put some distance between it and the background, a bokeh effect is achievable. Backgrounds fall shy of the smooth results you can get with an exotic telephoto like the Sigma 135mm F1.4 DG Art, but I’m happy that they avoid false color, texture, and hard edges, all factors that lead to distracting backgrounds.
Canon EOS R50 V, f/5.6, 1/60-second, ISO 125 (Credit: Jim Fisher)
