ISO is known as one of the exposure factors. The higher the ISO the more brightness. Camera manufacturers are even boasting about how high their ISO is going when they want to sell you a camera.
In this new video from Tony Northrup, he is explaining why ISO in modern cameras is fake. First things first, ISO is an international standard. ISO is an acronym for International Standard Organization. Back in the days of analogue cameras, they needed a standard for how sensitive film is to light. It would not make much sense to have two companies making two types of film, with different light sensitivity, calling both of them ISO 100.
Today many digital cameras are basically ISO-less. This is also called ISO invariance. It does not matter to the final photo whether you photograph it on ISO 100 or ISO 6400 given the shutter and aperture stays the same. Confused? Obviously, the ISO 6400 photo is brighter out of camera, but if you increase, the ISO 100 photo with the same amount of stops in post processing you will end up with the same amount of noise in the final photo as the ISO 6400.
As Northrup points out, that gives a potential for photos at ISO 3. Yes ISO 3. It is basically the same process as stacking images in post and averaging out the noise in the photo. Check an earlier article of mine to see how I apply this to my drone photos. What is really important for a clean photo is the "signal-to-noise ratio."
Check out the video above. If you are tech savvy this might not be new to you, but it is still very important to how you think about your settings when capturing your photo.