We can get some idea of the quality of the extreme ISO pictures on the new Nikon D5 from some sample image by Leon Ostrom of Randorn in a post on PetaPixel.
Not able to take away any images on a memory card, he photographed a series of test shots on the Nikon stand at CES 2016, then photographed the results displayed on the LCD screen on the back of the camera, both showing the full frame and a magnified detail, at Hi-1 (ISO 204,800) to Hi-5 (ISO 3,280,000).
Although these are only pictures of the image on the LCD screen.they give a very good impression of the possibilities of the camera, although the actual images could be greatly improved by appropriate noise reduction in post. Most impressive is the quality at Hi-1, which of course drops off as amplification increases. Hi-2 (IS0 409,600) looks to be usable for many purposes after noise reduction, while higher ISOs are distinctly emergency only.
Its a remarkable achievement, and one that makes me lust after the D5, though it isn’t a feeling I can sustain for long given the price and weight of the camera. But certainly it does make me hope for better high ISO and more affordable and lighter new models from Nikon. Even going back to DX with the D500 might be an option.
It also is a stark reminder of the ridiculous nature of the arithmetic ASA system. which was incorporated into ISO along with the much more sensible logarithmic DIN scale, where a one stop difference is an increase in 3, which makes it much easier especially when the ASA numbers get astronomical.
Back in the days of Tri-X, it was a 400/27 film (though we actually often rated it differently depending on which developer we were using and how we liked our negatives.) But its a good starting point for thinking about film speeds, and my starting point for this little table (more about film speeds for geeks on Wikipedia):
ASA Din 400 27 800 30 1600 33 3200 36 6400 39 12800 42 25600 45 51200 48 102400 51 204800 54 409600 57 819200 60 1638400 63 3280000 66
Either using this little table (or being able to divide by three) you can see that Hi-2 gives us a 10 stop advantage over Tri-X (or 8 stops over Tri-X pushed a couple of stops) which is certainly not to be sneezed at.
With the D700 and D810 I’m now working with, the practical limit I find is around ISO 6400 – so the D5 is performing at around 5 or 6 stops down the scale better. The D4 and Sony A7SII both claimed 409600 in 2014, so the D5 claims 3 stops more than them. It does seem pretty remarkable.
http://nikonrumors.com/2016/01/08/nikon-d500-specifications-and-features-explained-confidential-nikon-internal-document.aspx/
is a “leaked” Q&A on the D500 which does clarify many points I was curious about. Loosing one stop (and DX of course) but everything else, almost, eg shutter life, for 1/3rd the price of the D5 more than piques my interest, the D3 hasn’t become any lighter over the time I have owned it.
Yes, looks interesting but worth waiting for real reviews when its been out a while. Though from the Nikon video http://imaging.nikon.com/lineup/microsite/d500/ you seem to be at danger from lightning strikes near it. http://chsvimg.nikon.com/lineup/microsite/d500/common/pdf/technology-digest.pdf is a little more sensible. http://oleliodden.com/photo-gear/field-reviews/beta-test-report-nikon-d5/ is interesting on the D5.