In photography, there are a few variables we need to adjust in our cameras at any given time: shutter speed, aperture, and ISO. Sure, there is white balance and exposure compensation, Among other things. But only the three are essential to any photograph.
ISO, in particular, is something that you should never adjust unless you have to.
Two reasons, mainly.
- Higher ISOs drain your camera’s battery more because it requires more processing power from your sensor.
- Higher ISOs will cause more grain or digital noise in your photos.
So keep your ISO at its lowest of 64, 100, or 200 whenever you can.
Theoretically, the only time you should change your ISO is if you need to worry about controlling motion. At that point, if your shutter speed is adequate, then adjusting your ISO might be necessary.