How the Nikon Z9 electronic shutter works?

Question

The Nikon Z9 is the first professional photographic camera with no mechanical shutter, only electronic. So what's different about it from previous generations that have allowed this, and why it haven't been done before?

I'm looking for an in depth technical analysis of how this shutter works, so maybe as of today (Early november 2021) this information is not available yet.

Answer 1

There is nothing new in how the Z9's electronic shutter works... it is still the rolling readout/rolling shutter. What is new is how fast it works.

The Nikon Z9 (and Sony α1 and Canon R3) uses a new stacked CMOS design which is the next evolution in BIS (back illuminated sensor) architecture. The stacked design essentially allows for the designation of entire layers for a particular task.

And in the case of the Z9 it allows for extremely fast readout speeds, nearly entirely eliminating the rolling shutter effect (warping/banding) and allowing the shutter to sync with flash up to 1/200. It was/is primarily the inability of the rolling shutter to sync with flash, and banding under artificial lights, that required/requires the mechanical shutter to be retained.

The stacked CMOS design approaches global shutter functionality without the global shutter drawbacks (cost, reduced FPS, etc).

I cannot say if this is the exact construction of the Z9 (or α1/R3) as that hasn't been released AFAIK; but this is one example of stacked CMOS architecture (separating the memory onto it's own layer) as compared to conventional BIS.

Answer 2

Technological improvements in two primary areas have finally reached the point to allow this:

• Increased processing power available in a portable, battery powered device that doesn't create too much heat or deplete the battery too fast (though some might debate whether or not most of the newer mirrorless designs from all manufacturers sacrifice too much in terms of battery life, due more to power consumption of electronic viewfinders rather than processors).
• Faster sensor readout speeds that reduce the amount of rolling shutter effect with electronic shutters to the same amount or less as the amount of rolling shutter effect experienced with traditional mechanical focal plane shutters.

It should probably be noted that other camera makers have recently introduced cameras with similar sensors that could have left out a mechanical shutter as Nikon did, but instead chose to provide the options of either electronic or mechanical shutter to their potential buyers and users. The recent Canon R3 and Sony α1 also have similar backside illuminated stacked sensors that perform at about the same level as mechanical shutters in terms of rolling shutter effect.