Does using the 4:3 mode on the hvx cause res loss? As shooting in 16:9 is most people preference & mine, making a project for SD use can sometimes require 4:3 footage.
It does a "center extraction". So there's no digital stretching process going on. I did some brief comparisons of HVX vs. DVX in 4:3, and they seemed comparable in resolution in 4:3 mode.
You are using less pixels than the 16:9 image, however. It's just like letterboxing the 4:3 DVX image to get 16:9 in post. Some people call that "losing resolution," or more accurately "not using the entire resolution of the chip," but the HVX image itself isn't being degraded to obtain a 4:3 picture.