Which is better, Canon EF or RF mount?

In case you haven’t noticed Canon has a whole new camera lineup out for mirrorless and they called it the RF mount. Unlike the EF mount, RF mount is designed specifically for mirrorless digital cameras. EF mount was designed in the days of film SLR’s. Later in EF mount history it continued on as Canon’s choice for DSLR’s as well. That continuity in the industry’s transition from film to digital and the more modern design and philosophy of EF mount at the time it was introduced ended up being the #1 power play amongst all camera companies at the time. EF mount was able to transition seamlessly to digital and it exploded with the rise of digital photography and Canon became the #1 camera company in the world.

With that kind of success behind a product it’s no wonder Canon has seemed hesitant to ditch EF mount altogether. EF mount is a very modern design and it has proved capable of pushing camera technology to a high level.

The word of the moment in photography is “mirrorless”. And it’s no wonder really, the mirrorless cameras have eliminated a lot of the complexity in cameras and generally made them better in almost every possible way.

So it is then that Canon pretty much had to switch to mirrorless, the market was shifting hard in that direction and for good reason. Mirrorless has a number of intrinsic advantages that while not impossible to achieve in a DSLR would double or triple the cost of the system in a DSLR.

One of the miracles of technology is that it can do pretty much anything we can think of. But the question we have to ask is, just because you can, does it mean you should?

From a reliability standpoint it is hard to fault a mirrorless camera. It’s about as simple as a device can get. No more flappy mirror, and in some cases, no more shutter either. If you look at the internals of a modern mirrorless camera they’re actually not that complex. Sure the computer chips look super complicated but the fact is they’re really not that complicated either.

The big advantage of mirrorless is that the mirrorless cameras make it easy for the camera to see the image the same way we see the image. In a mirrorless camera the sensor is also the shutter, it is the mirror, and it is the focusing sensor as well.

While in theory a DSLR can focus as well as a mirrorless camera can, the fact is that as of right now in order for a DSLR to do that it is basically working as a mirrorless camera. With that in mind you have to ask what is the point of the mirror if you’re not even using it?

And that is the approach that RF mount takes. RF mount answers the question by saying there is no point to the mirror! The mirror adds a lot of technology and expense without adding a lot of benefit. The big advantage of shooting in mirrorless mode is that the camera can show the photographer what their current exposure looks like. Mirrors are not able to do that right now.

Another big advantage of mirrorless is that it makes getting *exact* exposures a walk in the park. Since the sensor is fully exposed to the scene as you frame your picture the camera can tell you with near perfect precision if even a single pixel is overexposed.

And, since the sensor is fully exposed to the scene the entire time you are framing the shot the sensor can now perform a variety of other computations that allow the camera to track objects on the screen and adjust exposure and focus accordingly if necessary.

Ultimately, mirrors were needed for film, and they are not needed for digital. The purest form of a digital camera is a mirrorless camera.

Technical Advantages of RF mount

RF mount has a number of technical advantages. One of the more obvious is how many communication pins it has to connect to the body with. RF mount has 12 pins vs EF mount’s 8 pins. Think of that like adding more lanes to a highway. The increased number of pins increases power and bandwidth possibilities for lens-body communications. For instance, many if not all RF mount lenses have motion sensors mounted within them regardless of whether they contain stabilization elements in the lens. That is a difference from older EF lenses many of which don’t have motion sensors in them. RF mount lenses include these sensors to better communicate camera position and movement for camera bodies that have IBIS. The extra pins provide dedicated channels for power & data to serve all the different systems such as the more elaborate stabilization electronics that are now present in modern lenses.

The updated mount also allows the camera body and the lens to synchronize their stabilization when a stabilized lens and body are used together. This results in an overall stabilization effect that is better than IBIS alone or lens IS alone. Now it is possible for the two systems to work together. All the RF lenses that have IS in them will achieve 6.5 stops or greater stabilization when used with a camera body that has IBIS in it. The new R3 promises to increase that by a full stop as well, so be prepared to see an even greater stabilization effect here.

On RF mount the speed of the electronics in the lens and body has also been updated enabling things like the AF to operate faster. The improved AF communication between lens and body allows the Dual Nano USM lenses like the RF 70-200mm f/2.8 to focus really fast.

Other advantages of the RF mount go beyond the electronics to the physical design of the mount.

I am not a lens designer so I can’t confirm this but the word on the street is that due to the reduced back-focus distance RF mount wide angle lenses are easier to design than their EF mount equivalents. This should enable even wider and better corrected rectilinear lenses such as the RF 15-35mm f/2.8.

And even though the actual lens mount is the same size as EF the effective size is increased because it is moved closer to the sensor. This allows for a very large entrance pupil (aperture) to be designed into the lens. In fact there is speculation that a RF 60mm f/1.0 may be in the works! How exciting is that?

There is a lot to be excited about on RF mount from a technical perspective.


A lot of people will say, well, I don’t want the camera to do it, I want to do it. In that case why are you shooting digital at all? Just buy an old film camera and go have fun. I know the power of film, some people are drawn to it and I half expect a backlash to all the digital wizardry. I’d be willing to bet that some photographers will try to rekindle the “old way” of doing things. Well, I’m sure they will have fun doing that but I’m not sure they will get better pictures than the rest of us…

In conclusion, RF mount is better than EF mount because it is a pure digital mount. RF mount was made for a digital age whereas EF mount was designed for analog film. RF mount is the future. Whether that means it is superior or not is up to you.







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