Hi;
"antiface detection" - LOL.
John, let's tackle one potential problem at a time. Have you done any back-focus tests with your units (four NX5's! Awesome)?
The test would be easy - just point it at some kind of a still-life about 30 feet distant, zoom all the way, manual focus sharp, and zoom out.
Here's an example that shows the problem:
Thanks!
Steve
Win7 Pro X64 on Dell T3400, MultiTB SATA, 8GB RAM Vegas 10e x64 DVDA 5.2(build 133) Sony HDR-CX550V