I could not get my D810 to start recording video with a Nikon T mount that is purely attached mechanically . I tried setting a lens in the the manual lens menu but this did not work. This mount worked fine with my D800.

I can take stills with the T mount attached and the video will record with no lens on the camera.

Any ideas?

Andrew.

When you switch to live view in video mode are you able to see anything on the LCD display? Is mirror going in up position? Or is it just not recording?

You can see the scene in Live View video mode on the LCD.

There has to be some setting or menu item that allows video with non CPU lens. The reason I'm interested in this is because a friend is lending me an older 105mm macro that I want to use for some video stuff.

I tried a T42 mount in my local shop and it worked! I'll have to try bellows etc.