How to Fix Grainy Photos - Portraits Refined portraitsrefined.com/fix-grainy-photosPrivate View Use the lowest ISO possible. Higher ISOs create more noise. So, using the lowest ISO possible will prevent grainy photos. With newer and higher-quality cameras, you can get away with an ISO of 400 or 800. However, it depends on your camera. Regardless, use the lowest possible ISO to get the best results.