Quote Originally Posted by .blank cd View Post
ISO is equivalent to film speed. In digital cameras, its a measurement of the sensitivity of the sensor. I use a lower ISO in situations where I have enough light, and when Im sitting on a tripod at night, higher ISO when I need the most light possible, like when Im handheld in a dim lit room, or at night with fast lenses wide open handheld. As you increase the ISO, the sensor becomes more sensitive to light, but after a certain point it starts getting grainy. The higher end cameras have more sensitive sensors.

Shutter speed is the speed in which your sensor shutter opens and closes. For example, 1/250 is 1/250th of a second. You use a higher speed to stop action or movement, like in sports; or to let less light in (given a constant aperture value)

Aperture value is how wide open your aperture blades are when the shutter is pressed. A good analogy would be the black part in the middle of your eye. The wider open it is, the lower the aperture value. Tighter its closed, lower. When you look at something, all that light information is coming through a single point in your eye, when your eyes dilate, like in the dark, its trying to let more light in.

Awesome, thank you for that.

What are your opinions of my camera? It's a Canon EOS Rebel XSI 450D. I got it for $250 with a 18-55