Video Assist 5" 3G Dark recording

I have the following system:
Old analog video system
BM Analog to SDI converter
BM Video Assist 5" 3G

Picture on screen for both analog videosignal and picture on Video Assist show good picture. Recordered video saved on SD card is dark and low details.
have tried different codex.

The screen on the Video Assist monitors is uncalibrated and cannot be adjusted outside of very basic brightness and contrast. It seems to be incapable of reproducing anything approaching proper black, probably as a result of the backlight. Because of this, I’d be very wary of judging critical exposure with the Video Assist, particularly on dark or night scenes. If you know how to use the scopes, they would be a safer option. Also, avoid False Color as that seems to be inaccurate as well. I’ve seen a 1.5 stop difference between false color on the assist and on my camera. “Tech support” say the camera false color is accurate, but can’t explain why the monitor should be different.