copied from the MCR42 user manual.
ENR-1.2*/ENC-1.2*: to use MCR42 with some type of camera (ex. Canon® C300, Canon® XF305, Sony® Pmw200, Sony® Pmw300, Sony® PmwF5, Sony® Fs7, Nikon® D600 or Nikon® D800, Canon® SD mark3...) which accept a signal with reduced dynamic. This type of expansion doesn't add artifacts to the signal and allows to have a less noisy signal. It allows to improve the quality of the audio registration (compared to the ENR/ENC standard) increasing the S/N ratio up to 15dB.
To use these expanders, it’s necessary to set ENR on the transmitter and ENR 1.2 on the receiver or set ENC on the transmitter and ENC 1.2 on the receiver. ENR-1.2 it’s used for the optimization of noise, ENC- 1.2 it’s used to optimize the voice.
I believe this 1.2 type commander setting will address "low" camera levels. Note v3.3 FW is needed to unlock these features.