Display OVF on laptop

Hi

I have a Nikon D810. Is there a way to display the optical viewfinder feed on a laptop screen?

Welcome to the forum! I think the HDMI port will display the viewfinder.

The thing you want is tethered capturing.
You'll need to connect your camera to the laptop by USB cable and you also need a software to do so.
Lightroom would work.

Daniel is right on with my thinking. Another option that I've used is the CamRanger for wireless tethering. There's both an app for viewing the camera, as well as one for controlling the camera ... so you can use the laptop to control and capture images, while an iPad or other tablet is used for the subject (or parent, or art director, etc) to view the images you're getting.

...and welcome to Nikonites!