No need to recapture! Heaven forbid…
The simplest thing to do is to render the entire timeline as a single file (or a sequence of them if necessary). This is simply accomplished by using export quicktime.
Open a new sequence and set this to be 4:3 (uncheck anamorphic tab)
Import the previously exported files back into fcp. Open the properties for these files (or file) and check the anamorphic tab. Drop this file(s) into the 4:3 sequences, and it will be letterboxed!
The nice thing about this workflow is the original export is nice and quick (no conversion), and the new letterboxed timeline will run in real time on most modern macs…
Happy outputting!
Editec Broadcast Editing Ltd
EVS and FCP specialists
Current Mac systems All Dual 2.7Ghz with Kona 2 and Digital Voodoo cards, 6Gb Ram, Sapphire, SCSI320 Medea and Huge Arrays.
FCP projects include Sky TV coverage of the Ryder Cup and US Open Golf – Live OB specialists. Edit/slomo vehicle.
http://www.editec.co.uk