[mst]

To my surprise, Capture One had a D850 in their list of supported cameras before I had the camera - and before it was available. But usually you're right, especially with exotic stuff. Or Fujifilm...

The RAW converters I use for the D3x and D7000 reviews were released in 2011... I don't have high hopes that they support the D850  
 

But no matter how many iterations you will go, the values on another system (body, lens, converter) will change again.

That was the intended message
 

I suspect, some companies are also fiddling with the RAW before they export it to an SD card.

Sure. Leica does, for example. Not necessarily with any influence on MTF values, though.
 

About the ratings: If there's a transparent system for ratings, why not? In fact it is quicker than reading. At the same time I sometimes miss aspects which are important for me - but do not influence ratings.

And that's the issue, as explained above already: there is no way to rate and at the same time match everyone's priorities. That's why we write 2 or 3 pages of text and include all the graphs. If we honestly thought that a simple rating would do, we could summarize the whole site onto a single page with just the lens name and the rating... something that has been requested very often already and we so far declined, for the same reasons already mentioned when discussing review ratings in general.
 

And when Klaus mentions to rate the Sigma even lower but went higher at the end because of the nice bokeh then I conclude: oh the ratings are more based on feeelings than on facts (which is normal, I'd say, as soon as one puts subjective points like handling or finish into the rating).

Handling and finish have no influence on the optical rating. Numbers do, for the most part, and then some personal impressions or priorities, I can't rule that out. We're humans, in the end, and shutterbugs and gerhads on top. We try to be as neutral as possible, though.
 

I see it from a readers side: OL/PZ doesn't create comparisons between lenses (like "how good are the corners of this lens at this FL compared to another lens").

I'm baffled, seriously. What else are the MTF charts there for?
 

If lenscore rated the lens, they use one sensor for all, so the results of the lenses are comparable, even if the system has oter issues.

And what does this rating tell you if you want to know how the lens performs on a sensor that is very different?
 

I don't care much about 1/2 or 1 stars difference. But I do care about 1 1/2 star diff beteeen a zoom getting 4, flaring like mad and a prime with 1 1/3 stop more speed and fully adjustable AF at 4 different distances - tis matters because sharp or not is more important than getting 10 lines more resolution in lab conditions. I don't want to create a big debate, but that lens is not worse at 14/2.8 than the 4 star Nikkor is. At least not (transfering stars into percent is ridiculous, I know) nearly 40% worse (4 stars 100%, 2.5 stars 62.5%).

I'm not sure why you keep coming back to this single point. Each lens is tested and judged across the whole specification set it offers. The Nikkor starts at f/2.8, and it is fairly great at its largest aperture already.

The Sigma starts with a bigger aperture, and thus is rated across a larger aperture range. At f/1.8, it shows weaknesses at the borders and corners. Which, by the way, I think can even be seen in the full res sample you posted (the lady at the lake). I don't find the border anyhow impressive in there and think they match the findings quite well.

If a lens offers a large aperture, we expect it to be great across the frame at that setting to receive a great rating,, when it comes to MTF, it's as simple as that.

Beside: looking at the available data, I still have doubts the Sigma matches the Nikkor at 14/2.8