There's a prominent podcaster who has been railing against Canon and Nikon recently because, as he says, their mirrorless cameras can't use lenses from their existing DSLR product line. While that's true in the cast of Nikon's mirrorless offerings, it's absolutely not true about Canon's M-series. But, that's not really the point that some people seem to be missing about mirrorless -- including some mirrorless camera manufacturers. Why would anyone want to stick a relatively monstrous DSLR lens on a compact mirrorless camera body, like a Sony A6500 or even a Fujifilm X-T2 body?
One of the advantages of mirrorless cameras is size. Once freed of the relatively large mirror box of the typical DSLR, manufacturers were able to design new lenses that took advantage of a relatively short flange distance (flange distance is the depth of the camera body, from the lens flange to the sensor). This allows for smaller, lighter lenses that balance well on diminutive camera bodies, like the Olympus Pen-F.
Sticking with our Olympus example, the comparable lens would be Panasonic's 12-35mm f/2.8 (Micro Four Thirds cameras have a 2x "crop factor"). The Panasonic lens weighs a mere 10.8oz (compared to the Canon lens at 1.5+lbs), and is only 2.7"x2.9" (the Canon is about 3.5"x4.5"). In other words, using that huge 24-70mm f/2.8L IS lens on a mirrorless body just isn't ergonomically ideal!
And besides, the point of these mirrorless cameras systems was to come up with a camera that was smaller, lighter, with equal-or-better image quality as compared to DSLRs. Putting that old, big, chunky glass on defeats the purpose.
Now, someone's going to start whining about their investment in all those expensive EF and EF-S mount lenses. Guess what? Canon's got you covered. Go ahead and buy their shiny new M5 body ... and the EF-M Lens Adapter (or a less-expensive third-party alternative). Your old lenses will work perfectly on the M5, at least until Canon gets around to making high-end glass in the EF-M mount. Canon planned for this, and used exactly the same electrical connections for both lens mounts. The adapter only needs to account for the different mount opening and flange depth.
So, you see, that podcaster was dead wrong -- Canon's existing lenses will work fine on their mirrorless bodies.
By the way, there is one camera manufacturer that did decide to make their mirrorless offering use the lenses from their DSLRs without the need for an adapter: Sigma. That's right, if you're one of the few who own a Sigma SD1, with it's SA lens mount, and you want to go mirrorless without having to worry about lenses, you can grab their sd Quattro body. They've incorporated the lens adapter right into the camera body, and pretty much negated the whole advantage of a mirrorless system. I guess it seemed like a good idea at the time.
And, here's another point. Most "experts" agree that the DSLRs days are numbered. They're like the dinosaurs. Start planning now, so you don't miss the boat.
Folks, if you got here from a social media link, and wish to leave a comment, please do so here. It makes it easier for various readers to follow the conversation. Thanks!