When using a Sony NX5U (AVCHD) I changed the aspect ratio to 4:3 in Menu setup, but when bringing into FCPX the video was 'stretched' horizontally. How can I make the video 4:3 ? Original files were brought in via ProRes 422. Would I need a plugin to retain the 4:3 ratio ? -KS
You simply keep the source as 16:9 and then make the sequence you edit it into 4:3 to determine the final aspect ratio.
When you edit 16:9 material into a 4:3 sequence you will get letterboxed pictures by default.
If you then want the image to fill the frame, ie no black bar top and bottom, you have to zoom into the image (losing the sides).