external webcam too dark topic

hi everybody, I need to use an external webcam on android device (android stick mk809III)

I use a logitech c270 (which I read is compatible as someone is using it), but the image is too dark (almost -2EV)

is there a way to tweak the signal in order to achieve this lost exposure in every app like camera and skype?

I tried on my samsung galaxy s5 and is correctly working...

thanks