So I am having experienced wildlife people tell me its not that fast and its not as good. Here is one here at POTN
FROM KICKFIPKID687---He is not the only one
""I've rented / tried the R5 twice now. Once with drop in filter EF-R adapter, since they didn't have the normal one.
Second time my buddy rented and let me use it for some days/split the cost. I tried with base adapter then and also RF 100-500.
Comparing to 1DXIII, overall it's a pretty nice body. But still has some issues/quirks and things to work out.
The animal eye AF can work really great, and is def. not a gimmick/can be super nice to have. Can work awesome for smaller birds/closer ducks and whatnot.
But when trying to Track BIF, my results were a bit all over the place. I was testing multiple lenses on the R5, with and without extenders.
I mainly use an older 500 F/4 L IS, which is showing it's age in terms of AF speed, so maybe not the best test. But it did perform really great on the R5 sometimes.
The R5 could sometimes lock onto birds within 1/4 second and hold as it flew over water and zig-zagging all over, using the full sensor/DPAF to track it.
However... sometimes when a bird was flying on a blue sky, or overcast sky, or even in other situations, it would just hunt and not lock... I would try 3-5 times as the bird was flying around me, and no matter what, it just wasn't having it, which was extremely frustrating. Even perched birds, sometimes it would lock behind the bird and not want to re-focus back to the subject, and i had to force it.
Also, using the RF 100-500, the focus could be extremely fast, as fast as the a9II and 200-600 when i tested that setup. But again, it would hunt sometimes/not want to lock, even with that native lens...
By comparison, the a9II with 200-600 almost never hunted for me in my tests, and would almost always "lock" the bird, although that camera still had plenty of out of focus shots as well.
As far as sensor quality, the R5 definitely is one of Canons best. I expected the noise to be more similar to my older 7DII, but it's actually very similar to the 1DXIII. You can crank the shadows like crazy, 4-5 stops in some cases, and see basically almost no color noise or anything. By comparison, the a9II has really HORRIBLE noise in the shadows sometimes, even uncompressed Raw at iso 250 or something. Can get super nasty green shadows/artifacts when only doing a slight shadow boost and nothing else. It seems like Canon has caught up/past Sony in some ways from what I've seen anyways.
Battery life on the R5 was pretty decent, but not super amazing. The issue though with that is.... if you're using mechanical shutter, your FPS drops from like 12 to 4-5 when your battery is 60% or less...
I was out shooting harriers/owls and suddenly my FPS just tanked and the EVF was super laggy and I didn't know what happened. Then realized/saw that my battery was lower and that's why...
You can switch to silent shutter to get 20FPS at full battery and I think maybe 12-14 at lower battery, but then your also in 12Bit Raw, not 14, so can't push the files as much.
On older firmware, not sure about now, I was also able to "overheat" the camera when I was shooting in silent shooting mode, doing short burts for 15-20 min.
I wanted to record a video of an osprey extremely close that I had been photographing, but then i couldn't because the camera locks you out of video then, and you have to power off the camera completely to let it cool...
This was even in 65F weather, with constant 10MPH winds, so definitely not HOT by any means.
Some other quirks of the camera are things like, EVF being black when you might need to react to a bird flying by (same as any other mirrorless), and then you go to take a shot and you can't see anything.
So you have to wait for the camera to wake up, or force the EVF to stay on, but then your battery life is going to drop really fast.
I also noticed if you are doing bursts, even with the Extreme PRO 128GB CFExpress card (1200MB/s write), the R5 can be buffering in some cases, and if you want to zoom back into 100% view on the rear LCD/EVF, it blocks you from doing it, until the buffer clears...which is super weird... makes no sense. When shooting photos i mean/not reviewing images.
Also the EVF I was seeing some kind of harsh glare/flare when the sun was somewhat behind me, making it hard to see what I was doing sometimes, especially when the EVF brightness is not that "bright" in daylight, even at its maximum setting. I saw more flare/glare in that finder than the 1DX for sure or other cameras I've used, not sure why.
Going to the 1DX Optical viewfinder is MUCH bigger and brighter and was almost night and day in that situation for me/much easier to see. But could be personal preference /some may not mind it.
All in all, i'm still tempted to get it, mainly for more "Reach" and eye af/other features, when it works well. But it's definitely not cheap and still has those quirks/issues I mentioned where the 1DX doesn't show that.
The 1DX you can still rip off shots and not worry about overheating/buffering/etc. Got way way longer battery life, dual CF Express, and so on.
Overall a more solid camera i feel like, or will be ready to go when you are. Just is too bad it's only 20MP, or that's my biggest "issue" with it yet. After coming from a 7DII with that longer "reach", even using my 500 + 1.4x on the 1DX, I'm losing some detail. Although getting more keepers, so that's a higher priority/better deal i guess."
So I see this at Fred Miranda and other sites....why are very experienced photographers telling a different story ??
flipkids post seemed extremely friendly and non biased towards mirrorless cameras