It is only suspected that Charles C. Ebbets took that particular photo.

The RCA Building Company had another two prominent photographers on site for the PR campaign of that day, Thomas Kelley (who took the photo of Ebbets here) and William Leftwich.

Back then it wasn't important who took the photo, the photographs were property of RCA, who'd later go through them and select the right ones for publication.

The one thing we do know about Lunch Atop a Skyscraper is that it was not taken by Lewis Hine, as sometimes thought. He was not there that day.