I hacked together a quick camera format control script. The internal Blender render settings are production oriented – hit a button and everything is set up for HD or PAL. I find that when I’m making images, I kind of scale the box until it frames things properly. Then, I have to do some mental arithmatic to scale it to the right resolution. So, I wrote a short script that lets you drag a slider to set the aspect ratio and then use a slider or some presets to get the right resolution. Its a subtle change, but I find it to be useful.
script at : http://www.screamyguy.net/camFormat/cameraSet.py