Strange behaviour of false colors mode on field monitor

Question

I just bought a Feelworld MA7 and did some test yesterday regarding false colors.

Here are my tests:

1) video capture of the scene, together Final Cut Pro X's oscilloscope:

2) photo of what the Feelworld MA7 field monitor was displaying:

Close-up on the scale:

We can see that although pink should be for totally black areas (IRE < 0), MA7's false Colors show pink even in areas holding information, like the left side of the t-shirt which, according to the oscilloscope (and according to our eyes), hold some luminance values.

To push the test a little bit further, I used a lut which applies false colors onto clips in FCPX (https://luts.iwltbap.com/false-color-lut/). Here's the result with the corresponding scale (I think it's Atomos' scale):

In this case, the results are much more intuitive (and better corresponding to the oscilloscope): nowhere do we see dark purple (IRE < 0 on this scale).

Why is that? And ultimately, can I trust the Feelworld MA7 field monitor to help me accurately expose my scenes?

Answer 1

Such cheaper monitors often don't have enough power to calculate it correctly. Often they are just added as a sales pitch. I wouldn't totaly trust it, but you can take it as a rough estimate.