If you've not had much experience with metering, then you can use these photos as an example of how the SS and apeture work together. In each photograph, the amount of light being exposed to the sensor is the same, i.e... larger apeture/shorter shutter, or small apeture/longer shutter. The end result was the same amount of light which gave the same brightness. In "P" Mode, you are letting the camera choose some of the variables to achieve the "proper" exposure. Even though these images look the same, there is a variable, which is difficult to see here. It is the DOF. I'm working on a drawing that I think will help explain the DOF considerably, because working in the optical industry, it is something I deal with almost daily. Take these photos and use them as a guide for experimentation. Put your camera on "M", set your apeture, ISO, and SS to the same as one of these photos, then start changing just one, for example, your apeture. take a photo with every possible different f/stop and see what it does, then go back to the original numbers and change only the SS, then do it again with changing the ISO. You will start to see what difference these settings make, and also how they interact with each other
Kevin
