[JJ_SO]

The bullshit is solely yours. SPEED is about the number of photons collected by a sensor pixel.
And an X mp FF sensor pixel collects roughly 4x (give or take) more photons than an X mp MFT sensor.

To compare sensors with different ratios and different resolutions is the first bullshit coming into life, into real life.

For a clean equlivalencing you have to take care of ALL and not only of some parameters. So far I don't know an APS-C sensor of 45 MP or more, I also don't know any "FF" sensors with another ration than 3:2 - and µ 4/3 - it's in the name - has a 4:3. This alone makes the whole equivalencurbation empty, point- and meaningless, it has nothing to offer for a good or better end-result.

But what can one do against concrete in skulls...

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...When I watch a photo, I don't think - oh, that's f/4. I think - that DoF is nice (or not) and the image noise is fine (or disturbing). And I will think of many other aspects, too ... which is why I prefer MFT. ;-)....

That I call a blunt lie (except the bit that you prefer µ 4/3  ). When you look at a photo, you will never know the exact DoF, because you can't compare it to an "equivalent" one from another camera - you will react emotionally on it, you want to see clearly what's the interesting point or story in the photo is. And if the photo can trigger your emotions well enough, then all what you explained about equivalent becomes rather pointless as noise is simply less disturbing for the majority of people INCLUDING you, you couldn't even tell the difference (if it doubles) or say that's taken with ISO 3865 as that number alone doesn't say anything.

It's comparable within the same sensor's range, but from one brand to another the same ISO number will look different - ISO also is just a number.

In terms of DoF you also pretend there's the same effect of DoF, no matter what lens in front of the camera - then why do you point out differences in terms of bokeh in your reviews? And in this discussion pretend that f/2 with all lenses of a certain focal length, adapted to the same sensor and also everything else really exactly the same will always give the same effect? From which aperture on bokeh changes to "nervous background" is not the same over all given lenses with identical FL.

In a picture there is no way to measure the DoF, as it is always going through sharpening, it's depending on clean or polluted air, quality of light, even the amount of motion blur. Measuring airy discs is one thing - how they look as a collective in the finished picture is another story. And this story doesn't include only one mathematical formula, it's far more complex.