A while ago, I came across a great place where you can learn about digital photography. Click HERE to check it out!
I've joined their mailing list as well and receive weekly emails with great articles on different subjects. One in particular that I received last week was about the art of exposure and the three important elements you need to understand to get a right exposure and also learn how they work together. The article mentioned really neat metaphore. Here it goes:
Many people describe the relationship between ISO, Aperture and Shutter Speed using different metaphors to help us get our heads around it. Let me share a couple. A quick word of warning first though - like most metaphors - these are far from perfect and are just for illustrative purposes:
Imagine your camera is like a window with shutters that open and close.
Aperture is the size of the window. If it’s bigger more light gets through and the room is brighter.
Shutter Speed is the amount of time that the shutters of the window are open. The longer you leave them open the more that comes in.
Now imagine that you’re inside the room and are wearing sunglasses (hopefully this isn’t too much of a stretch). Your eyes become desensitized to the light that comes in (it’s like a low ISO).
There are a number of ways of increasing the amount of light in the room (or at least how much it seems that there is. You could increase the time that the shutters are open (decrease shutter speed), you could increase the size of the window (increase aperture) or you could take off your sunglasses (make the ISO larger).
There were other metaphors but I liked this one the best. I know, it sounds like trying to explain something to a child, but I'm more of a visual person and when metaphors or illustrations are used to help me understand something, I can visualize it in my head and it makes a greater impact in me and it's stuck in my head forever :)