Nothing wrong with Michael’s answer, all totally correct. If, however, you want to use your quicktime for anything else (and don’t want FCP to re-render it a different size, which could cause a longer export) I would recommend the advice he gives for changing the playback resolution in Quicktime Player. It leaves the movie untouched as an anamorphic full resolution file, if you ever want to bring it back into FCP.
Personally, I always stretch the horizontal dimensions. If you want the math, since you are going to 16:9 just divide the vertical height by 9 and multiply it by 16 to get the correct horizontal figure to change your sequence to – so for PAL SD you end up with 1024×576… Nothing wrong with shrinking the vertical either, just like ’em big, and the playback seems to behave the same 😉
Ben
Editec Broadcast Editing Ltd
EVS & FCP specialists for live OB operations.
Producer/Director “The Supercar Run” now available for international distribution from http://www.electricsky.com