We are in fact approaching an interesting point here: the validity of testing methods against other testing methods.
Absolutely agree.
There is a difference between 'claims' and facts.
One method-user 'claims' his methods are better than others doesn't necessarily make this a fact.
I am not expert enmough to judge the one or the other,
Unfortunately, me either.
@JKoerner, as an investigator you might want to share your "all other sources" quoting links to these other sources.
I have seen DXO, who claim a significant lead and see the measured D850 performance as the best they have ever seen in their lab...
Who else is there with open spec testing?
Well, there aren't a lot of sources about the D850 right now, but it was almost universal that the D810 offered the best Base ISO performance ... from DxO, to DPReview, to SenScore, etc.
As far as I know, only DxO and PTP offer graphs, which are similar, with the extreme figures at Base ISO being a bit different.
Eventually, SenScore will chime-in.
Lloyd Chambers gave "an impression" in favor of the D850, but "his impression" isn't measured testing.
However, most compelling to me is the fact
Nikon pushed its own D810 (and, now, D850) forward as Nikon's own champion.
This cannot be overlooked IMO. It's one thing to have some skills in trying to "measure the results of others"; it's quite another to have
the skills to design, and the means to produce the best sensors in the world (at both Base ISO
and high ISO).
The fact Nikon can do both ... and positions its own D810 and (now) D850 as the uttermost of its own Base ISO technology, basing its 100 year celebration on the latter ... I just refuse to believe Nikon itself doesn't know "which end it up" with regard to its own cutting-edge technology in both directions.
For example, Nikon advertises/prices the D500 has having great AF tech, significant fps, and very good high-iso ability ... but
not as good as the D5 (in anything).
Nikon also positions its own D750 (which, by every other measure, besides PTP) ranks
second, behind the D5 in high ISO, behind the D810 in base ISO, but is a good "middle ground" between the two (better high ISO than the D810, better base ISO than the D5)
but beating none of them in the extremes. The D750 is priced/positioned/spec'd as a very good
mid-FX Nikon.
These facts, prices, and commercial placement by Nikon are not 'by accident'; they are
by design.
With everyone else echoing this sentiment, and with Nikon itself (in both its price and placement of the D750), I just find it difficult to accept "the one" guy standing alone, offering a graph which shows the D750 offers better base ISO performance than Nikon's own flagship, Centennial champion.
My own experience, as an investigator for both civil and criminal litigation (but, admittedly, not an engineer) defaults back on what the proverbial "reasonable man" would conclude.
IMO, it is not reasonable to believe everyone else's conclusion is incorrect, except Bill's, including the multi-billion dollar Nikon Corporation, who makes all of these items ... and markets/positions each product according to their capabilities.
In the end, I do not believe Nikon 'accidentally' made the D750 with a better base ISO rank than the D810/D850, nor did they do so on purpose.
Based on all other evidence, I believe Bill's graph/placement is somehow flawed.