Sorry if this has been talked about before. Most people familiar with photography know what ISO means when talking about film. One thing I have never been able to understand is how ISO can relate to a sensor inside a digital camera. How can the sensor become more sensitive by changing the ISO? I can only guess that it is a software function, which to me is pretty lame. It makes me think that ISO is just a "feel good" setting on digital cameras. I personally do not use high ISO on digital. I simply slow the shutter speed instead. Of course, I have experimented with the setting and saw the extra grain with the high ISO settings. Is there anyone that can explain why an ISO setting is included with a digital camera and does it really work? And if so, how? Thanks!