Quote Originally Posted by Kayaker72 View Post
But that said, the natural conclusion to ISO invariance is that you can under expose certain modern cameras with little penalty, and I do use this in my photography and this is one of the reasons I bought the 5DIV (that and f/8 AF points, etc).
So wouldn't this make sense?

If your camera is set on the exact same shutter speed and aperture the sensor gathers the exact same amount of data regardless of the ISO setting.
If you adjust your picture to the proper exposure in post the data was always there, you would only be changing the point in the process it is done.

Quote Originally Posted by Kayaker72 View Post
  1. The camera diode/sensor received different charges at certain key ISOs, so the charge in step 1 changes at certain ISOs
I have never heard that one, why would it?

I do remember old conversations or debates about noise. A certain amount of noise is introduced at the sensor, additional (spatial) noise when you increase gain.
So perhaps if someone could explain how increasing the gain works, does it change the signal to noise ratio?

Engineers:
https://www.sis.se/api/document/preview/907324/
https://webstore.ansi.org/Standards/...SAAEgLtPPD_BwE