There will always be a newer, better camera at any given time
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There will always be a newer, better camera at any given time. No one knows exactly when, or even if, an R5II will be available to buy. No one knows when the next firmware update for the existing R5 will appear, or what that firmware might enable. Everyone's guess is as good as anyone else's. Only a few product planners, engineers and department directors in Japan know for sure, and they aren't talking to the public any time soon.
So, if you need or really, really want a great sub-1series high megapixel mirrorless Canon camera now, buy the R5; you will not regret owning this amazingly capable instrument.
If time is irrelevant to you, wait however long you want; why not even wait for the Mark III version if time is of no real consequence, and I am not being sarcastic in saying that.
Just know that the leap in capabilities from the 5D4 to the R5 is huge, especially in the area of autofocus; for me and my work it is the first truly dependable and nearly always useful (and better than my own manual ability) focusing performance that I've experienced, nearly freeing me to just take pictures, to concentrate on composition, lighting and timing, with just some attention paid to exposure. For me, that has been nearly revolutionary, a much greater advance than even the media transition from film to digital. Of course, YMMV.
As a now semi-retired professional, I may eventually buy a later version of my R5 as well, but, I don't think that, aside from some likely video performance improvements, the leap from R5 to R5II will be anywhere near the chasm that exists between the 5D4 and the R5. For stills, you likely will get some incremental benefits from the Mark II version, but whether those would tip the balance for you would likely be debatable and more depend on exactly your interests and styles of shooting than any overall evaluation of the new camera's improvements.
Good luck out there.
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