Understanding ISO in Photography: What Finally Made It Click for Me in the Field
When I first started learning photography, ISO was probably the setting I understood the least.
Shutter speed made sense because I could see movement blur or freeze. Aperture made sense because I could see depth of field changing in the image. ISO, however, felt far more abstract. I knew it made the image brighter or darker, but beyond that I mostly treated it as a setting to avoid touching unless absolutely necessary.