Quoted By:
While ISO does have something to do with ADC gain, ISO is generally a meaningless number because manufacturers try to make it so that ISO "100" will provide similar exposure across all cameras and film given the same shutter speed / aperture.
So ISO 100 on one camera and ISO 100 on a completely different camera will have different levels of gain in order to give the same exposure.
That's why ISO 50 on any phone camera still looks like actual shit, pixels are tiny so gain needs to be higher to get an acceptable exposure given a 1/30 sec shutter speed, or whatever.
You can't really have discussions about "ISO" or talk about 'decreasing it' for this reason.
