1. Shutter speed: the amount of time the film or digital sensor is exposed to the light ,the numbers are represented in fractions of a second until you reach a shutter speed of 1 second or more. ie; 60= 1/60th of 1second, 125=1/125th of 1 second etc. Fast shutter speeds freeze action, slow ones allow blur.
2.Aperture: The size of the opening of the diaphragm inside the lens. The numbers used here also represent a fraction so the larger the number the smaller the opening, due to the fact that 1/22nd of "as wide open as possible" is a smaller opening than 1/8th. These numbers are usually prefaced by a little curvy "f" (f-22, f-8 etc.) this comes from the French word "finestra" which means "window", rather fitting I think.
The neato thing (that's right, bringin' back the word "neato"! Deal with it!) about the aperture is that it not only affects how much light is allowed in to the film or digital sensor, it also controls what is referred to as depth of field (DOF), which is a measure of how much will be in "acceptable" focus from the camera position to the horizon, or sky or farthest visible object. A large aperture (small number ie; f-1.8) will give less DOF, which means you will have a narrower slice of space from front to back be in focus. I like to think of it as a noodle making machine, like the Play-Dough kind we had as kids, with a smaller opening the noodles are more focused, longer (shutter speed) and tighter, while larger apertures are more sloppy, shorter and fatter.
3. ISO (What many film guys know as ASA): Means "International Standardization Organization" Who's motto is "Same, more same!" They often stand about outside places that offer things that are not standard, and chant "What do we want? MORE SAME!, When do you want it? ON A STANDARDIZED SCHEDULE!" (not RLY) but yeah,...ISO controls how sensitive the film or digital sensor is to light. The higher number the more sensitive. This control factor has less play in how the image actually looks aside from one caveat, noise. Noise is the stuff in some images that looks like static, or little dots. Many sports, photojournalism and fine art photographers are much less concerned with noise. The more sensitive (ISO 800, 1600 and up) the more noise will become apparent.
Either the camera can control these three things to give you a "proper" exposure (proper according to the camera, not your wants), or you can, its always better if you control at least two of these factors. The thing is a lot of compact cameras do not allow to control any of these directly save for ISO, so you have to learn how to trick your camera into creating the image that YOU want, not the image that the camera thinks you should have.
Think in terms of a bucket at a water spigot, ISO=the size of the bucket, Aperture is how much you open the spigot and how MUCH water flows out, Shutter Speed is how long it takes to fill the bucket to the top.
Take this understanding and re-read your manual, the part about what each mode is and what it does for the final image, ie; sports mode=fast shutter speed therefore it stands to reason that one will require a wide aperture, BUT in many cameras the programmers understood that things move quickly in sports so you do need to maintain a little bit more DOF, to keep your subject in focus as they move about, so it will most likely increase the ISO sensitivity to allow for such a fast shutter speed, at a medium-wide aperture,...
Have fun tricking your camera into doing what you want. Oh yeah BTW might not be a bad idea to take some test shots to really get a grasp of these concepts, you'll find out really fun stuff like when you're zoomed way in the DOF is WAY less than it is when you are shooting something at a very wide angle, take notes on what you are doing, and the use the notes later when looking through the images on your monitor, it helps, trust!
I promise I'll be back sooner next time with some "How I shot it" stuff where-in I will share an image and explain how I shot it!
