[Klaus]

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.

[wim]

However, light gathering is the same as any F/4 lens, just over a smaller image circle.

Yes, and assuming the same megpixels the MFT sensor collects 4x less light - so it's back to "f/8" here as well.
A lens without a camera is just a paperweight.

It's the end result that counts - nothing else.

Come on, Klaus: that is due to the sensor, not the darn lens. And I said as much anyway. The sensopr is 4x smaller, area wise, and there collects 4x less light, hence 2 stops, hence has more noise under the same circumstances as with a FF shot. The lens is stil an F/4, not an F/8. The only reason it has the DoF of an F/8 FF lens is also because of the smaller sensor. It doesn't make it an F/8 lens, however, and I am really getting rather irked about this, this "fake news". It si time we start putting this in the correct perspective.

From a design and manufacturing PoV it is an F/4 lens, whether you like that or not.

Regards, Wim

[Klaus]

Wim - I use MFT privately. I prefer it over other systems. Yet I do accept the realities and I do not have any issues with them.

If you have any interest in the FACT that the 12-100mm f/4 has a TRUE aperture of f/4 - well, Ok. That's perfectly fine and I do not dispute this at all.
However, for me, that's just a number in EXIF data and something that I choose to achieve a certain DoF in the final image.
That number (to achieve the desired DoF) differs depending on the sensor format. As such the number alone is of no special interest to me - at all.

Within the scope of this discussion, it's DoF and image noise that counts in images - and that's a combination of lens and sensor capabilities.

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. ;-)

FACT is that 12mm, 1/100s, ISO 100, f/4, 20mp on MFT gives me the same DoF, FoV, exposure, shutter speed and noise as 24mm, 1/100s, ISO 400, f/8, 20mp on FF.

[Rover]

Yeah I had said something along these lines. Nice to see that I'm becoming a meme maker around here.
...

And proof-reader as a side-job with lots of time to kill, as there's not much to proof-read these days. All so good?

It's the other way around - I have little time that isn't taken by work, so I'm not really paying attention. Even though I talked to Markus once and said that I'd be doing some of that thing along the way... Shame on me.

But the whole proofreading inclination, I guess, just comes with the territory of being an editor / journalist in daily life. Up until pretty recently, I had a habit of pointing out verbal mistakes to people, but it had been brought to my attention that reaction to this... well, may vary.

[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...

---

...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.

[Rover]

You guys are going to get this thread locked.

[Klaus]

I have to know the numbers in order to be able to determine the effect on the image.
That doesn't mean that I care for the numbers - I only care about the effect.

And to repeat myself - the effect of the following numbers is identical (give or take an insignificant amount):
MFT: 12mm, 1/100s, ISO 100, f/4, 20mp
FF: 24mm, 1/100s, ISO 400, f/8, 20mp

[JJ_SO]

One more or less about this subject... who really cares?

Mathematically all is fine, but just by excluding "disturbing factors"
Realistically the equation sometimes leads to an idea, but honestly all that stuff is only relevant once - when buying a smaller camera and already knowing (really knowing, not just having some blurred memories) about FL from old 24×36 mm film times

Everyone going into µ 4/3 with a fresh start has simple no clue what 35 mm FL mean - until he or she get a glance through a 24×36 mm finder.

The end result counts - very true. And equivalence doesn't matter in a photogs life.

[Klaus]

Correct.

[JJ_SO]

Yeah!