Fast forward and we're entering 2026... making a 50mm f/1.0 lens on Canon’s RF mount is easier than doing it on the old EF mount but it’s still a huge challenge. The main reason is the shorter flange distance on the RF system. EF lenses have to sit farther from the sensor that means designers need big, complicated rear lens groups to bend light properly. The RF mount brings the rear elements much closer to the sensor,so it’s simpler to design the lens with fewer compromises.
Even with the RF mount a 50mm f/1.0 is still very demanding. The front element has to be huge to gather enough light and keeping the image sharp at the edges is tough. Designers need special glass, aspheric elements and precise alignment to control blurring, vignetting and other optical problems. That’s why lenses like this end up big, heavy and expensive.
We can compare this to the Leica M 50mm f/0.95. Leica’s M mount is even smaller and has a short flange distance which helps them make an ultra-fast lens. But the lens is still massive and very expensive because the optical challenges don’t go away. Canon’s RF mount gives similar freedom so it’s more realistic for them to make a 50mm f/1.0 than it ever was on EF.
