In articlehttps://www.imaging-resource.com/news/2018/07/17/pixels-for-geeks-a-peek-inside-nikons-super-secret-sensor-design-labwe read this with information passed along from the head of Nikon's sensor development team:This is one area where Nikon’s dedicated sensor design has paid off for them: The D850 has the first true ISO 64 capability in an SLR. (Other cameras have special “Lo” ISO settings that will get there, but those come at the expense of poor tonal qualities and blown highlights.) Sanbongi-san told me that they developed the D850’s true ISO 64 capability in response to requests from motor-sports shooters, who wanted to shoot at large apertures and slow shutter speeds, so they could pan to follow the race cars while dramatically motion-blurring the background.I don’t know enough about sensor design to understand the details of what’s involved, but when I asked Sanbongi-san what his team’s proudest achievements were, he mentioned the D850’s true ISO 64 first.But this chart certainly implies that this was already true for the prior model:http://www.photonstophotos.net/Charts/PDR.htm#Nikon%20D810,Nikon%20D850I'm a D810 user but I really don't care if the ISO 64 is "fake" according to some criteria, when I already know the actual benefit that it accomplishes for me in practice. That was just an odd thing to read.

Nikon USA quotes:"The D810 truly raises the bar for image quality and dynamic range. ... 25% faster frame rates (5 fps), a wider ISO range of 64-12,800 with low noise throughout, ..."It might simply be a mistake on Imaging Resource whether it comes from them or a Nikon publicity gnome.

That is a either a mistake or a marketing thing. Both the 810 and 850 do ISO 64.DxO measures ISO and the measured ISO for both cameras at ISO 64 was;D810 = ISO 47D850 = ISO 44

nuke12 wrote:That is a either a mistake or a marketing thing. Both the 810 and 850 do ISO 64.DxO measures ISO and the measured ISO for both cameras at ISO 64 was;D810 = ISO 47D850 = ISO 44Now that is interesting.  I wonder why Nikon didn't at least call it ISO 50 which would have been more accurate?

nuke12 wrote:That is a either a mistake or a marketing thing. Both the 810 and 850 do ISO 64.DxO measures ISO and the measured ISO for both cameras at ISO 64 was;Beware. DxO 'measured ISO' is not what it appears to be. It doesn't measure the ISO.D810 = ISO 47D850 = ISO 44The ISO of both cameras, when set to 64, is 64 (within a fraction of a stop). What DxO's so-called 'measured ISO' means, is, if shooting in raw, you could expose for that ISO (47 for D810 or 44 for D850) and still fit in the full ISO specified exposure range (i.e. you wouldn't clip the whites).

Ernie Misner wrote:nuke12 wrote:That is a either a mistake or a marketing thing. Both the 810 and 850 do ISO 64.DxO measures ISO and the measured ISO for both cameras at ISO 64 was;D810 = ISO 47D850 = ISO 44Now that is interesting. I wonder why Nikon didn't at least call it ISO 50 which would have been more accurate?Because it isn't 'more accurate'. ISO 64 is ISO 64 on those cameras. DxOs name for what it measures is inaccurate.