struggling with life and theory here... so, shooting at 4K DCI (4096x2160) and putting into a UHD timeline (when in Rome...) I know I am scrunching pixel together, and am fine with that. And the top/bottom letterboxing is black in 2.40:1 aspect matt.

BUT, if I want the clips pixels to match up perfect - as opposed to said scrunch - where do I put the numbers in to make sure it is right? I don't have Vegas in front of me... GUESSING in the PAN CROP box thingy?

Has anyone done this, and is there a noticeable quality improvement when you line the pixels back up?