But if you are down below a certain limit, there is not human discernable difference (around 20msec latency as I recall) And that's what we should be looking at: When is it "good enough" that we cannot perceive the lag.
The ballpark varies depending on a person's age (though doesn't vary
much between early teens and middle age) and, of course, what they're used to and small variations in every person's eyes and brain. A small minority of people genuinely can't spot or feel 50ms-ish of delay, for instance. The vast majority of people can spot down to about 16ms. Some people can spot down to around 8ms, though testing that is highly debated and 10ms is a commonly-agreed compromise. People used to seeing displays and video content at high refresh rates and frame rates are more tuned to spotting this kind of lag than someone who never looks at a screen; if you've spent half your life picking apart frames at 60Hz (16ms) and now you've spent the last few years picking out frames at 120Hz (8ms) or more, you're going to be able to spot when a device is operating 50ms behind. So your tech bros, your gamers, and your professionals will,
mostly (of course there will always be exceptions, and no, naming one person does not disprove or prove anything) see and/or feel even the minimum lag that a mirrorless system is capable of.
So yes, if a camera can be made that brings lag down right to the absolute bare physical minimum time it takes for light to simply travel, be converted and the shuter to go off, then yeah, that kind of time should be "good enough" for us to not perceive lag unless we were specifically looking for it. But, realistically, there are no displays (for viewfinders or otherwise) that can meet that speed, no CPUs that can meet it, and simply too much going on inside a camera for that kind of speed to be reached. Even then, it still would technically not be eliminating lag.
I'm not saying we can't get a camera to be fast enough for practical use, just that the phrase "eliminate lag" is making an extremely inaccurate claim.
Imaging-resource.com measures shutter lag.
And they do so terribly inaccurately, as you'll find if you search around as many people have torn down their process. They don't include
any of the wider system lag, either mechanical and software, let alone display lag.
For an example of how inaccurate their speeds are, go check Canon's own literature on the 1D X and R's lag;
even Canon's own marketing doesn't claim speeds that fast.
Here's a bit of insight into the battery life on the R3
This photographer(Damir Senčar) who was given an R3 from Canon to use at the Olympics, posted a pic of the shutter count. QUOTE: 16379 photos with one battery on Canon EOS R3
Number of shots taken is an erroneous, disingenuous, and highly unrealistic way of measuring battery life. If you put one of these 20fps or 30fps cameras on a steady surface, set it to medium jpg with a gigantic card, and just hold down the shutter, you can ''shoot'' tens of thousands of images in just 10-15 minutes. The battery will still be at 80% and that makes the camera sound like it'll last forever. A sports pro shooting 16k in one go is not remarkable in the slightest. If it's shooting at a locked 30fps he could've done that in just over 9 minutes.
This is why the CIPA ratings are always much lower. Though they still count the number of shots taken, which isn't actually helpful, at least they factor in leaving the camera to idle, reviewing images, navigating menus, etc.
A more helpful measurement of battery life would be the actual
hours the camera lasts turned on, without going to sleep or turning off key functions. I don't care if a camera can shoot a billion photos in one go at a high burst rate; I care if I have to keep turning the camera fully off for it to last until the next event. A 1D or 7D can be turned on in the morning and not turn off, or even go to sleep, for the entire day, and only the 7D will need its battery changing. The R and R5, for me so far, need the battery changing at least every hour and a half, no matter whether I've taken 200 shots or 2000.
I'm not saying the R3 will have a poor battery per se, just that quoting a large number of shots, for any camera, is not helpful.
