Just got myself a 500D and trying to learn the basic settings so I can take good photos. I'm confused about Aperture and ISO though. I know aperture is the whole in the lens so to say to let light through and ISO is the sensitivity of the sensor to the light. But after reading a few sites I'm still confused how they relate to actual photos and the actual difference in the quality when from what I can see they both limit the light coming in in a way. Even the basic websites seem to be too complex to read on this. So can someone explain it like there explaining it to a 7 yr old ditsy blond girl thanks. Shutter I'm fine with mostly as that's the amount of time to let light in which is pretty easy to understand especially for photos of Ferris wheels, car trails etc.