Nikon Z8 Launched

Like the flagship Nikon Z 9, the Z 8 is at the industry apex of speed and versatility. At its core, Nikon’s powerful EXPEED 7 image processing engine has been combined with the proven full-frame (FX-format) 45.7-megapixel BSI stacked sensor with a scan rate so fast that no mechanical shutter is needed.

ᔥ ULTIMATE HYBRID PERFORMANCE. AGILITY WITHOUT COMPROMISE. THIS IS THE NIKON Z 8.

From a press release available on the Nikon USA site. No translation required (for me). The emphasis on the word proven is mine — indicating to me that this isn’t a new sensor.

Edit to add:

~www.nikonusa.com/en/nikon-products/product/mirrorless-cameras/z-8.html#

IMO there were no such mules or prototypes.
For the Nikon Z8 to be delivered to users in May, it has to have been in manufacturing already for some time.
That means it was in testing for several months - Ricci said he has been testing for 2 months before announcement. It would have been in testing in Japan several months before Ricci got it.
That means that the design and build was finalized probably last year.

how does that prevent testing other prototypes last year ? same body - different Sony Semi tech sensors (either off the shelf or custom made for Nikon specs)

If you look closely enough, you can find at least one picture of a Z8 mule that circulated. While I won't say exactly when certain mules/prototypes were in others hands (it might give away the source), those happened last year ;~).
Moreover, you misunderstand the use of mules/prototypes. They're often used to verify decisions that need to be made. I know of a couple of instances now where a product was already starting to move to manufacturing, but an internal electronics change was decided upon based upon mule/prototype evaluation. You can design the digital board size/shape prior to locking down a few decisions that go on the board. In the case of the Z8, deciding upon using the Z9 electronics essentially intact was easy enough to have ready quickly.
The real long-lead item that locks down first is image sensor. The lead time for being on fab is enormous. You really need to lock that decision as early as possible because these days, ILC sensor runs on the fabs are tightly constrained because you're not making a lot of them. The Z9 image sensor, for instance, probably had fab runs of 50k units or so in its first year. Perhaps it was more if the yield was low, but the fact that we're now seeing the same sensor used in a product that will easily outsell the Z9 seems to indicate that yields are under control.

I doubt it very much that Nikon had any other plans for the Z8. Lots of fakes were circulating and IMO some deliberate misinformation to lead people astray.
It is more likely that Nikon had their hands full trying to reduce the Z9 to Z8 dimensions without creating massive heat issues with 8K.
I imagine also that they had to redesign the internals to ensure that almost all of Z9 capability could be squeezed into a smaller body.
Apart from that timing is everything - so they had to keep it quiet to avoid impacting Z9 sales, and only announce when they had already got production going. As any delay in delivery will massively harm Nikon.

It is more likely IMO that they are testing 60+ mp res Z7 II replacement (no stacked sensor). And maybe the Z6 II replacement. But these are not in the same category.

It is extremely unlikely Nikon had other stacked sensors to play around with for the Z8.

Vast amounts of speculation on speculation at this point… not really adding to the understanding or enjoyment of the rest of us.

To what end?

When folks at Lens Rentals get a chance to open one, they usually do a good assessment. They know from experience what breaks easily vs. what lasts a while.

I ran it through the DeepL translator rather than Google and got this:

The Z8 uses the hybrid body approach they've used on pretty much all but the big, vertical grip pro cameras: a combination of metal and Sereebo (carbon fiber infused polymer). All of the parts that need alignment on the Z8 are mounted to a metal frame, the rest of the body is the carbon fiber type material.

In terms of "build quality," I'd judge the Z8 to be just fine, and probably more hardy than the D700, actually (that all metal frame has issues of its own, which can make some damage unrepairable).

It will be good to head more about this Sereebo (carbon fiber infused polymer) that is a great hard wearing heat dispersing material - according to what I read
Have folk who are complaining not heard from our military folk who say all their armament is made from a mixture of composites and metals -- they are REALLY TOUGH and hard wearing.
See:
www.compositesworld.com/articles/seerebo-cfrtp-sheets-saving-the-earth
www.greencarcongress.com/2019/05/20190508-teijin.html
en.wikipedia.org/wiki/Carbon-fiber-reinforced_polymers

I'm not sure I agree with either comment. First, take a look at any Z9 tear down and you'll see that the digital board doesn't extend down into the lower part of the body, because the battery chamber is down there. While I expect to see a slightly different digital board in the Z8, it's size will be quite close to that of the Z9 board. The big differences will be the different card slots and connectors that are attached. If I'm correct about this, the engineering required for such a repurpose is relatively simple and easy to do.

As for heat issues, I'd expect them to do basically the same thing they did with the Z9, which is to put a heatsink frame over the digital board. People think that because the Z9 body is so big that it has a lot of "air space" inside in which to dissipate heat. That's not really true. Again, look at any tear down. Will there be heat issues with the Z8 with the smaller body design? Maybe, but I suspect that will be more due to the fact that there isn't a metal frame throughout the camera.

You mean like the one they publicly demonstrated from Tower Semi? ;~) It's abundantly clear that Nikon has been doing stacked sensor work with multiple partners for some time. To date we've only see one appear in a product.

Going by patents filed I agree Nikon is continuing research into sensors.
But I am not aware of a joint demonstration of sensor design with Tower Semi. Please would you share a reference to that?
Nikon did talk about a 1-inch high speed stacked sensor, but as far as we know, that's just research and not in any sensor product in the market.

Obviously no one can know what prototype sensors Nikon has access to.

Someone knows. Multiple people even. It’s just not you. Or me.

More info regarding Sereebo-p - teijin-mobility.com/en/new_tech/sereebo_p/

Given Z7 and Z6 were all magnesium alloy bodies, it is not clear why Nikon chose to use Sereebo in the Z8.

Above appears to confirm that magnesium alloy body is better for heat dissipation.

Agreed. brochures.nikon-asia.com/Brochures/ML/Z8_Master_Brochure.pdf

One explanation: Advances in materials science make the new material feasible for and/or better suited to the product.

Its not new and was used in D5300, and also in D750 and D500.

The process and or material may have been improved. Composites are a moving target.

As I've noted elsewhere, the heat sink over the digital board on a Z9 essentially connects to the magnesium frame area just under the Rear LCD. This is a double-edged sword. Yes, it disperses heat from the sink, but it also is retaining the heat within the body itself. I believe that the biggest benefit of the Z9 design is actually the battery chamber having heat dissipation via the frame. The parts that heat up most during 8K/60P are image sensor, EXPEED7, CFe card, and battery. The Z9 improves that for everything over the Z8, but mostly the card and battery. Note that the card and battery are close together in the Z8. I'll bet that is the true gating issue.

Concerning the durability for the D700, I have one data point to share. Back in 2009, I took my D700 to South Georgia Island in the Antarctic. On a windy day, I unwisely set up my D700 mounted to a 70-200/2.8 AF-S VR (version 1) on a fully extended tripod. Not sure why I didn't pay attention to the wind and not holding onto that set up. Of course it took no time for the wind to blow the whole thing over. The body and the lens hit hard rock. There is now a permanent dent on the side of the D700, but the 70-200 had no apparent damage. Both continued to work fine for the rest of that trip.

Two months later, at home I noticed that the 70-200 had manual focus issues, but AF was totally fine and that was why I didn't even notice the issue. Nikon wanted $550 to $650 to fix the helicoid and I declined. Instead, I used that money towards a 70-200/2.8 AF-S VR II, as I knew version one had a lot of edge quality issues at 200mm.

I still own that D700 today and it is still working fine. Of course, if a different part of the body hit the ground, the outcome could have been very different.