hey guys, I just got my cannon rebel xti and in need of some help, i've read about aperature and shutter speed and all that, my question in when I take a picture do I just adjust everything(aperature/shutter/iso) so that my exposure is neutral? like for example, I was reading this one write up about aperature and shutter speed and it said f5.6 should have a shutter of 1/30 to get proper exposure, however when I take a shot in my cam 5.6 at 1/30 inside the house would be underexposed so I have to change the shutter to let more light in and inturn gets blurry at times. am I on the right track here?