NP. ISO refers the "film" speed setting -- i.e. how much light is required to properly expose the "film". Low ISO's need more light but produce more vibrant colors and smoother pictures. High ISO (like 1000) don't need as much light (i.e. you can use faster shutter speeds) but are grainier and less vibrant. For nice shots you'll probably get the best results around 100-200 ISO. Up at 500-1000 ISO the shutter won't have to be open as long but the pic will be grainier. High ISO are typically used when you need to have a fast shutter speed (like taking an action shot) to prevent blur but still need the "film" to get exposed. Since we are using tripods, taking a still image (no movement in the photo), and have the time, a lower ISO (100-200) will give a beeter quality looking shot. In short if you take 2 pictures with the same aperture but different ISO's, the higher ISO will have a faster shutter speed to achieve the same exposure (but be grainier) than the lower ISO.