You asked

Is the nikon d810 good for video?

The Nikon D810 page is about stills, mainly landscape work, and it doesn't cover the video features I'd want to judge it by, such as a flip-out screen or a microphone input. So I can't call it a good video camera from here.

Two things do carry over. The D810 has no stabilisation in the body, so for handheld footage you'd want a stabilised lens. The Nikon AF-S 16-35mm f/4G ED VR and the Nikon AF-S 24-120mm f/4G ED VR both have VR. For a wide, vlog-style look, the Video page explains what to look for in a camera and a microphone. The Nikon D810 page has the full specs.

Written by Claude from this site's pages.

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