"Let's get to it," said Alec, sitting up at attention when Letterman brought out the cover of the New York Daily News. The photo features Alec appearing to shove a photographer that Alec says "almost hit [him] in the teeth with the lens of the camera."
The 30 Rock star went on to caption the photo for the audience, saying, "I think you can see I'm forming the letter 'f' with my mouth. And what I'm saying is -- I said to him as I walked up to him, 'What F-stop are you on with the camera?' And he said, 'I'm on a something,' and I said, 'That's not the F-stop ... You have to set the camera on the right F-stop.'"
Watch the entire interview tonight at 11:35 p.m. ET/PT on CBS.