@raja manuel Why did you think that Canon will make it impossible to use it's lenses by other camera users? Canon have an RF - EF adapter. Sony users now have to two adapters instead of one. RF to EF and metabones FE to EF adapter. Can't they use it in this fashion?
First of all, let me thank you for mentioning me correctly
I don’t think Canon have an RF-EF adapter. I have only seen 3 adapters mentioned, and all are EF to RF adapters (Plain, Control Ring, Drop-In Filter). I don’t think an RF-EF adapter will be possible.
Existing Canon flashes are compatible?
I would assume this is the case. I am not aware of any reason why flashguns are affected by mirrorless/reflex mirror design, though I vaguely remember that Canon was rumoured to launch mirrorless optimised flashguns, but I thought that was only to do with the size of the flash for those who wanted a very compact package.
There is no official word (or I am yet to watch/read about it) about EF M to RF adapter or what's their stand on EFM cameras/lenses.
I haven’t heard of an official word either (though I may have missed it) but I think we can safely rule out an EOS M to RF adapter, based on the explanations I have read. The M has a flange distance of 18 mm, i.e., 2 mm shorter than the RF. It will have to be mounted inset into the RF mount for it to be able to focus on the sensor, and I haven’t heard of any sign of the RF mount supporting such inset mount capability.
I suppose the possibility exists that Canon could write some code into RF bodies that make them instruct the M lens to front focus, thus getting it to focus on the sensor. I don’t know if Canon will bother, as there may be performance issues that make the exercise unviable. And how many Nikon DSLR users put APSC lenses on their full frame bodies? Investing that much money into the body and then compromising it with an inappropriate lens is unlikely to appeal to many buyers.
The question assumes greater significance when posed the other way around: will an RF to M adapter be provided? The advantages are obvious: M-series users can build a collection of RF lenses before upgrading to a full frame, and RF-series users can use an M series as a backup or BTS camera. Unfortunately, and perplexingly, this also will not happen. There is only a 2 mm difference between the flange distance of the 2 mounts. A 2 mm thick adapter will not be possible. Canon seems to have chosen to sacrifice the M series and many people are wondering if its future is in doubt, though it is possible that Canon has user data to show that very few EF-S system buyers ever bought EF lenses beyond the 50mm f/1.8, and have preferred to have 2 distinct lens systems. Canon might still surprise us, though. They are still releasing new lenses for the M mount, so the system isn’t going anywhere in the near future.
Eye-AF is definitely a pleasant surprise. Portrait photographers, who are likely to be the primary audience for this camera, should be very pleased.
Canon have also released a whitepaper on the EOS R system. I would recommend this as a good read even for those who are not interested in the Canon ecosystem because it gives a good explanation for why the EF lens mount was no longer good enough, and the RF system is necessary. The shorter flange distance allows using a larger rear element that increases image quality, and avoids having a large front element. This enables creating lenses that are smaller, lighter, and optically superior than the older generation. Another interesting point is that the RF mount is also designed to permit higher volume and speed of data transfer between lens and camera which Canon seems to think is very important. They claim that this allows them to create much better images using DLO within the camera (for JPGs, and I suppose video) and on the desktop (for raw). This allows users to use the f/1.2 fully open without aberrations, and also avoid diffraction losses when the aperture is fully stopped down.
The whitepaper also says that Canon chose the 20mm flange distance because it had to be short enough to deliver superior optical performance while being long enough to provide sufficient mechanical strength to mount heavy lenses. The last point is interesting, as Sony has chosen a slightly shorter, and Nikon a much shorter, flange distance.
If I’m reading the whitepaper correctly, IBIS is coming – or at least, the design parameters support it. Whether Canon will actually implement it is a different question.
The detail in the whitepaper suggests that Canon was not rushed into an announcement by Nikon’s launch, though it is possible that both were rushed into launching products before the holiday shopping season begins due to Sony’s growing market share. I think both have launched minimum viable products, and we are likely to see more bodies, accessories, and capabilities appear as they become more comfortable with the direction the market is heading.
