1. What is ASA? The ASA was the American Standards Association for film in the united states until 1988. 2. How much more exposure is there as you change from one ISO setting to the next? ISO exposures Double as they increase and are halved as they decrease. 3. What is the main drawback to changing the ISO from low to high? The higher the ISO you use the more grain is present in the photograph. 4. In what type of condition might you want to use ISO 400? You might want to use ISO 400 in shade, Indoor light conditions, or when using Flash. 5. When might you want to set the ISO to 1600 or higher? You may want to use ISO 1600 or higher when there is very little light a available or you absolutely need a high shutter speed to stop action or avoid camera shake etc.