How does ISO work on a camera?

[hy]

ISO doesn’t change a camera’s sensitivity to light. It is basically a gain setting that amplifies the base signal at the base ISO, which also brings up the noise floor. This results in more grain and less dynamic range. You can definitely see that this is the case with ISO invariant cameras like the Sony A7Siii.

It’s also not entirely true that your image will get noisier as you increase the iso. Some cameras have dual conversion gain where, one gain stage is optimised for better dynamic range in good lighting and another gain stage for low noise in low light. The A7siii is also another great example of this, it has a high conversion gain at iso 1600 in standard colour and iso 12800 in S-log 2 or 3. For eg. if you’re at iso 10000 in S-log 3 it would actually be noticeably noisier than iso 12800.

[calvinwerry]

Of importance is the final use of image. Recording a instance for personal reference is different than getting an image ready for publication in print. A full banner size web image may need better grain than a smaller in text image.

[skullxd]

My days of improving my skills day 5❤❤
I am now getting more interested

[benjamin.kelley]

Loving this series! I wanted to mention that for beginners, ISO doesn't increase amount of light hitting the sensor and can't really considered as part of the exposure adjustments - either there's more light or less light. Aperture, Shutter speed, and amount of light are the only things you can change to actually make the entire image brighter or darker.

[Tamay.]

ISO is a disk image for computers to for example an operating system