Can I shoot in 16:9 then change it to 4:3?
Of course you can set your project up so that it will output a 4:3 video. However, keep in mind that there are only two ways to achieve this:


Nr. 1 You crop the video, which means you will lose stripes of the video at both the left and the right side.


Here's an example:




Nr. 2: You resize the 16:9 input video so that it fits in the 4:3 output video. I wouldn't recommend this though, since the video and everything in it will be deformed, which looks completely aweful.


So if this is your input:



It will result in this output:



Both options result in a quality / information loss. How about shooting in 4:3 at a higher framerate? You could easily lower the framerate in editing to achieve your desired effect ...