This is an excellent reference for people just starting out. The relationship of shutter speed and aperture seem to be one of the most difficult areas to comprehend for people new to photography, especially aperture. It is easy to conceptualize shutter speed, ie., 1/30 is half, or one stop different than 1/60. But the relationship of f/5.8 to f/8, although the same, is not nearly as easily grasped and it gets even more confusing when you are talking about half or third stops like f/4.5 and f/6.3, which is also 1 stop