Should You Buy the New RF 45mm f/1.2 or a Used EF 50mm f/1.2 L?

Canon's RF 45mm f/1.2 STM and the old EF 50mm f/1.2 L USM now sit close enough in price to make the comparison real. The used market has pushed a once-aspirational L lens down to roughly the cost of a modern budget prime, which forces a genuine choice.

That collision is the subject of a head-to-head from Gordon Laing, who tested both lenses moments apart on a Canon EOS R5 Mark II. The new RF 45mm f/1.2 STM runs around $429 while a used EF 50mm f/1.2 L USM in excellent condition costs just a bit more. The older L lens is heftier, weather-sealed, and shipped with a hood, while the RF 45mm is about half the weight, adds a customizable control ring, and takes cheaper 67mm filters. Both lenses focus at nearly the same speed, roughly half a second to pull between subject and background.

Sharpness is where the age gap starts to show. Wide open at f/1.2, the older EF 50mm actually looks slightly better defined in the center, but the newer RF 45mm pulls ahead in the far corners, helped partly by a flatter field and a heavier vignette that darkens the edges. Close both down toward f/5.6 to f/8 and details even out across the frame. For close-range work, the RF 45mm resolves crisper detail on the focused subject, and the EF 50mm doesn't match that close-up sharpness until around f/2.8 in Laing's test. Bokeh tells a different story, with the EF 50mm rendering backgrounds a touch softer and less busy, though the gap is smaller than you might expect.

The bigger question here is what "character" is worth as older glass slides into affordability. Canon designed the EF 50mm f/1.2 L in 2006 for full-frame DSLRs, and its softer, creamier rendering was baked in by the optical priorities of that era. Adapting it to an EOS R body works fine through an EF-to-RF adapter, and the same adaptability lets you mount it on almost any mirrorless system, a flexibility RF lenses don't offer since they only fit Canon mirrorless. That one-way compatibility shapes the decision as much as sharpness charts do. If you shoot a smaller body like the EOS R8, the RF 45mm balances far better at 346 g versus 690 g for the EF with its adapter attached. If you still own a Canon DSLR, the choice makes itself. The wider trend worth tracking is Canon reviving the look of a beloved vintage lens in a modern, attainable prime, giving newer shooters a taste of rendering that used to demand flagship money.

Both lenses use an inner barrel that extends while focusing inside an outer sleeve, so fitting a filter seals the front section on either one. Neither includes optical stabilization. When pointed at the sun near f/16, the nine-blade RF 45mm and eight-blade EF 50mm produce noticeably different diffraction spikes, down to blade shape rather than count, and Laing frames that as pure personal preference. 

Laing's honest split shows in his verdict: his head picks the RF 45mm for lower weight, greater sharpness, and a slightly lower price, while his heart leans toward the EF 50mm for its softer rendering and the appeal of owning a former hero lens for cheap. Watch the full breakdown above to see the side-by-side portrait and bokeh samples and decide which rendering style wins you over.