I am normally a pretty modest person, so I don't know why trying to explain photography keeps leading me to discussing topics that are making me blush! Let's see if we can keep this tutorial out of the gutter so to speak :)
Three Components of Exposure
ISO, Shutter Speed, and Aperture
Remember these charts from school? I know, I hated them too... but I think it gives a good visual representation of how these three are related. When you make a change to one of the components, you will have to adjust one or both of the others as well.
ISO ~ This is how sensitive the camera is to light. The lower the number, the lower the sensitivity. The higher the number, the higher the sensitivity. For example. If the sun is shining bright, you will want to use a low number like 100 or 200. If you are inside the house or shooting outdoors on a cloudy day, your number will be higher. As I've said before, I do not leave this setting on automatic. I manually set it based on what I think will be my approximate settings and adjust from there. I've had more than my fair share of photos ruined because my camera jacked up the ISO and I forgot to check. If I have to adjust it, I am always responsible for the settings.
Shutter Speed ~ This is how fast or slow your shutter opens. Think of your eye. When you blink quickly, not much light enters your eye. But when you open your eye and leave it open for a while, much more light enters. When there is a lot of light available, you can set your shutter speed fast... this is good for sports, movement, quick toddlers... but when there is dim lighting, your shutter speed will need to be slower (leaving your "eye" open longer to allow more light to enter). But with this comes the possibility of blurry photos. As a general rule of thumb, if you are hand holding your camera, you do not want to have your shutter speed lower than 1/60 sec. And that is just for camera shake. If you have something moving, it will be blurry with such a slow shutter speed.
Aperture ~ Think of this as the pupil of your eye. When you go into a dark room, your pupil dilates (gets larger) to capture more light. When you step out into the sun, your pupil constricts (gets super small) to minimize the amount of light entering your eye. Now this is the part that confused me to no end. A higher aperture (letting in more light) is actually a lower f-stop number. If you want to restrict the light, you would use a higher f-stop number. There is something else that plays into this and that is depth of field. The f-stop number you choose will determine your depth of field. This is that natural blur that you see in photographs that when mastered can create visually pleasing and gorgeous photos.
If your head is spinning, don't worry. I will go into each one of these individually and walk you through them.
Homework for Tutorial #2
Put your camera in Manual Mode. Do not worry about having a properly exposed photograph at this point. I just want you to listen to your camera. Set your shutter speed to 1/8th of a second (which is very slow) and press the shutter. Now set your shutter speed to 1/500th of a second. Can you hear the difference? What do you think is happening in each of the shutter speeds. Which one will have more light entering and which one will have less light?
Continue forward to ISO
Continue forward to ISO
Capturing the Moment <3