There's a reason ISO 50 needs to be unlocked to be used. It's not actually ISO 50. It's ISO 100 being reduced in camera to ISO 50. The same as shooting ISO 100 and then in post bringing the exposure down a stop. I would never shoot with it.
Exactly. There's no real benefit to ISO 50, except perhaps convenience if you're shooting in Av mode and want a stop slower shutter speed. But if a highlight would be blown at ISO 100 with a given aperture/shutter combo, it'll be just as blown at ISO 50.
Neuro, my tests indicate differently to this. Iso 50 highlights are clearly more blown. I can never contradict you, so please tell where I am going wrong here..