Rewind back to 2013. Mirrorless cameras are in full swing, gobbling up the low and prosumer ends of the market, and amidst all the fuss, Canon puts out its prosumer offering, a seemingly tepid update to the 60D, the 70D.
Olympus launched its pro model that year, the OM-D E-M1, Panasonic released its smallest model, the Lumix GM1, and Sony announced the birth of their now-flourishing full-frame mirrorless system cameras with the a7. Canon’s only offering in that space was the EOS M, which had pretty slow autofocus and didn’t really win the hearts and minds of consumers.
On the surface, neither did the 70D, but hindsight being 20/20, we should have recognized it for what it was: Canon’s true first, and actually quite good, foray into mirrorless cameras, except that it had a mirror.
I’ll explain. Buried in the spec sheet of the 70D was a revolutionary autofocus system designed specifically for live view, and by extension, the electronic viewfinder of a mirrorless camera, such as the recently announced EOS R. To that point in 2013, most mirrorless systems used contrast-based autofocus systems to focus right off the sensor, or pixels scattered across the sensor for phase detection duties. That said, one of the biggest advantages to focusing on the sensor directly is accuracy. Mirrorless systems generally had more accurate focusing because there was no optical viewfinder to gum up the works.
Canon basically took the existing concepts of on-sensor focusing and put them on steroids; 80 percent of the EOS 70D’s sensor did duty for phase detection autofocus. It meant very fast, very accurate autofocus without the back-and-forth hunting commonly seen with contrast-based systems. The coverage was almost across the entire frame. The company accomplished this feat by splitting each pixel’s photodiode to do double duty for focusing and image-making.
This system was called “Dual Pixel CMOS AF,” which was unfortunately a term that caused many eyes to glaze over and not give the system a second look. Canon pressed on with the name and the system, though, rolling out this feature across its DSLR and cinema camera lines. The latter, along with the EOS R, gained the ability to use this system to have a manual focus assist in the form of two triangles that converge on the selected point of focus until they’re green, a very handy tool for those that want to focus on their own.
Taking Dual Pixel CMOS AF out of the DSLR and Into Mirrorless
Things got better along the way. After the 70D, the 7D Mark II added the ability to control the speed how fast the system would rack focus (though this was somewhat limited by the lack of touch-screen on this model), and both the 7D Mark II and the 70D’s successor, the 80D, gained the ability to continuously focus with Dual Pixel AF while firing off still shots. The 80D gained a significant increase in image quality compared to the 70D as well, being the next generation of Dual Pixel CMOS AF. The 1DX Mark II, 5D Mark IV, and 6D Mark II brought this speedy AF to full frame DSLR models.
Along the way, Canon decided to bring the technology to the M mirrorless line with the M5 and its successors. This was a big step for the company. No longer would you have to hold a DSLR at arm’s length and use the rear screen for focusing, you could get the same smooth focusing through the electronic viewfinder, with all the other benefits that come with that, such as being able to preview your exposure, focus peaking, and customizability. This was, in a way, the test bed for the next big thing.
There was a time when the company wouldn’t even apply the term mirrorless to their cameras, even the ones that didn’t have mirrors (like the EOS M series). Fast-forward to 2018, and the tagline right under the name on Canon’s website for the EOS R is “full-frame mirrorless camera.” Clearly, the winds are changing at the big camera companies.
The most important part of any modern camera, right after image quality, is autofocus. Dual Pixel CMOS AF has come a long way and matured into a very fast and capable system from the 70D to the EOS R. While Canon may have seemed late to the mirrorless party, the truth is, they were working on it alll along, right in front of our faces.