Either my understanding of or the Nikon PV button function is convoluted.
Here's why -
The focus indication is pretty reliable in the D810 when a lens has a minimal amount of focus shift (e.g. an Otus) and a number of other compositional factors are in control -focal length, f stop and distance to subject and their interrelationships.
Without the PV button depressed you are focusing at wide open, in this case an Otus 55mm. With the f-stop set in the camera at f 2.0 the shift is minimal and sharpness is retained. As one goes up to f4 or higher they can rely increasingly on DOF to cover any critical focus errors as long as the subject is far enough away to allow deeper DOF to come into play. But this isn't always reliable. As subjects are nearer, critical focus is lost as the DOF contracts. In order to work around this, one has to use the PV button.
However, when one presses the PV button while looking through the OVF the focus indicator isn't shown.
Thus it's impossible to focus under the actual aperture the image will be captured and have the assistance/confirmation of the OVF internal focus indicator at the same time. (If anyone knows a setting that can change this, please advise)
Based upon this the only 'workaround' is to use the live view on the LCD in conjunction with a loupe, activate the PV button and then achieve critical focus through the loupe and LCD in live view.
Seems like Nikon (and Nikon seems to be a way more responsive company than Sony) could easily fix this.
Any reason Nikon can't make it possible to use the PV button and the focus indicator at the same time while using the OVF ?