I am a little turned around on one specific aspect of shooting for green screen. I understand I can turn my camera 90degrees to take advantage of the greater horizontal resolution. What I don't get is, won't that essentially reduce the size of my image on the CCD's. I know I can set the framing of my camera to fill as much as possible but only within reason. It seems to me that I am I am loosing an awful lot of image. Does it actually make sense to flip the camera when the imagers are so small?
You would be taking advantage of greater vertical resolution, as you would be shooting in a "portrait" orientation. Typically used for a single person shot; humans are more often in a portrait orientation. And, the chip turns 90 deg. with the rest of the camera, so you're still using the same area.
Exactly- it works best with subjects that are tall and narrow and would gain additional frame area by re-orienting the camera vertically. For short and wide subjects stick with the standard orientation.