3D or just effective Depth of Field?

I watched some great video tutorials I came upon by a professional photographer Mike Browne. For the first time, I have found someone know knows how to explain things in a language I understand.

Mike explained that, using a telephoto if you want to understand how Field of View of Depth of Field work on a telephoto lens, to try to take a shot of the same subject at the various focal lengths on your lens. And that's what I did: 75, 100, 135, 200 and 300.

This image popped the most and the whole exercise was a real eye opener albeit before an 8am breakfast at the Bedford Street Diner.

Jet lag probably had something to do with that, mind you.