How many modern mirrorless lenses rely on digital corrections? Some of them, most of them… or all of them? I own a lot of mirrorless lenses and I’ve tested a whole lot more, and my experience is that it’s pretty well all of them.
Now I’m not saying digital corrections are all bad. I actually think that they free up lens designers to tackle more serious optical issues. But the fact is that practically every modern mirrorless lens uses digital corrections to fix lens distortion, sometimes to an alarming degree. One example is the Canon RF 24-50mm kit lens, which has so much distortion at 20mm that the corners are black.
So what digital corrections do with distortion is push the corners outwards so that the fill the frame and straight lines are actually straight. One downside is that this ‘stretches’ what resolution the lens has in the corners even further. This is a particular problem for the Canon RF 24-105 f/4-7.1 lens, which has really soft corners at 24mm. Another is that if you shoot raw and you’re using a camera (like Canon’s) which doesn’t embed a correction profile, you’re reliant on your raw processing software to have a matching profile. That’s fine in Lightroom, but not in Capture One, which doesn’t really stoop to kit lenses. There’s not enough manual distortion correction available in Capture One to fix the 24-50mm.
The fact remains that mirrorless cameras do give lens makers an easy ride. Why? Because a digital viewfinder always gives a digitally corrected image, where a DSLR’s optical viewfinder shows what the lens actually sees.
But look, let’s say you don’t have a problem with digital corrections – Lightroom users won’t, and in-camera JPEGs will be fine. The fact remains that mirrorless cameras do give lens makers an easy ride. Why? Because a digital viewfinder always gives a digitally corrected image, where a DSLR’s optical viewfinder shows what the lens actually sees. With a DSLR, lenses have nowhere to hide, but with a mirrorless camera all their sins can be hidden away.
Incidentally, I want to take issue with another modern conception – that modern mirrorless lenses are much better than old DSLR lenses. I don’t agree. My Nikkor AF-S 24-120mm f/4 is better than both of Canon’s 24-105mm lenses, even the f/4 L lens. It’s not a big difference, but the Nikkor is definitely better in the corners. Maybe because it had to be corrected optically and not digitally…?