We've had a few opportunities to play with Nikon's first full-frame mirrorless Z7 now – which is due in the shops any day – but Photokina 2018 was the first time the company had its 'baby' brother, the Z6, on show. It's essentially the same camera except the sensor 'only' packs in around half the number of megapixels, at 24.5Mp, compared to 45.7Mp.
Externally the two cameras are identical, bar the 'Z6' badge instead of the 'Z7', and the functionally is largely the same in both, with the menu system, buttons and other controls all behaving in the same way. So the differences are purely down to the megapixel count.
Of course, 24.5 million pixels is hardly a trifling amount, it exceeds the number in Nikon's top-of-the-line D5 DSLR by some margin, for example, and is only significantly beaten by the D8xx DSLR line. But what it lacks in the headline-grabbing megapixel stakes, we found it to outperform the Z7 in many other areas – all of which are a direct consequence of the different sensor.
Frame rate and file size
Stick the camera into high-speed continuous shooting mode, and machine-gun rate of the 12fps shooting speed makes the Z7's top speed of 9fps seem positively sluggish when you fire them side by side, as we were able to do on the Nikon stand, where the cameras were set up next to one another. This actually matches the sport shooter's favourite, the Nikon D5. It's all thanks to the latest-generation Expeed 6 processor having to process files that are around half the file size.
Another benefit of this reduced file size is that you can shoot longer sequences of shots on the Z6 before the buffer becomes full and camera starts to slow down – we measured this to be around 3 secs on the Z6 vs 2.5 secs on the Z7 – and due to the greater fps, this works out at around 36 shots for the Z6 vs 23 for the Z7.
Not only is writing to the memory card quicker, you'll also be able to fit many more images onto the XQD card. Processing the smaller images in software should be a little zippier too – though we weren't able to test this as Nikon wouldn't allow us to use our own card in the camera.
ISO and AF performance
The larger individual photosites increase the ISO performance of the Z6's sensor too – and scrolling through the available ISO range revealed a native range from ISO100-51,200 (which can be expanded to a lower setting of ISO50 and a top setting of ISO204,800). This compares to the Z7's native range of ISO 64-25,600 (and expansions to ISO32 and ISO51,200), so that's an extra stop unexpanded, and two stop expanded). While we couldn't take our shots away for detailed analysis, zooming in on the rear LCDs showed that the Z6 indeed exhibited lower noise at these high-ISO settings.
Changing to single-point AF mode reveals another difference in the sensor. The Z6 has 'just' 273 selectable autofocus points arranged in 21x13 grid, while the Z7 boasts 493 AF points in a 29x17 grid, so the Z6 doesn't offer quite as precise autofocus placement. In practice, though, we found that having fewer AF points made it quicker to move around the display to pick the point you want. And both mirrorless cameras outperform all of Nikon's DSLRs by some margin – with the top-end D5/D850 managing just 55 AF points clustered around the centre of the sensor, rather than being selectable over the entire display.
Price and availability
Then there's the price; the Z6 will be significantly cheaper than the Z7, at £2099/€2399 (or £2699/€2999 with the 24-70mm f/4 kit lens, or £2199/€2549 with the FTZ adaptor). It's sure to attract many enthusiasts who can't quite justify the £3399/€3899 body-only price of the Z7.
You'll also have to wait a little longer. While you should be able to pick up a Z7 in the next day or two, you'll have to wait until the end of November for the Z6. But we reckon the wait will be worth it, and if you don't need the insane level of detail that the Z7 offers, then the Z6 offers you essentially the same camera at a handsome discount.