ISO controls how much light is let into your camera lens. The lower the number the lower the sensitivity of the film and the finer the grain in the shots you’re taking which will be a brighter shot where as if you use a high number you will get a very grain like image. On most cameras the ISO is automatic and the standard number the ISO will be on is about 400. I am going to take a shoot of close ups but also landscapes and I am going to try out a high number to get a oldfashioned natural grain effect. I will also use a film log in my sketch book to record what I did.
These are some photos I gathered from the internet to show you ISO.