It's not often that camera manufacturers deliver a huge update that may be revelatory to the cameras abilities.
Today, Nikon released the Z9 firmware version V5.10 which adds features that respond to the needs of professional-level video recording.
A new [Shutter mode] has been added to movie recording, allowing the user to set the shutter angle to one of 15 steps between 5.6 degrees and 360 degrees. This eliminates the need to select a shutter speed whenever the frame rate is adjusted, allowing users to always achieve optimal motion blur at the desired frame rate.
Most mirrorless or DSLR cameras don't offer a 'shutter angle setting' for video recording. So if shooting video, shooters opt to manually choose a shutter angle of '180 degree', meaning the shutter remains open for half the frame's duration. This setting is widely regarded as a balanced compromise between capturing smooth motion and preserving detail.
For example, using the 180 degree rule would mean that if you were shooting at say 25 frames per second (fps) your shutter speed would be 1/50. For the ability to use normal 'half speed slow-mo' it would be 50 fps @ 1/100. Super slow-mo would be 100fps @ 1/200.
Another V5.10 firmware update addition is that users can now change the colour of the Zebra pattern display, as well as customise the size, transparency, and display position of brightness information displays such as the histogram and wave-form monitor. These capabilities were incorporated to make video recording easier by allowing the user to confirm appropriate exposure, even when recording high-contrast scenes.
You can access the V5.10 firmware update here.