I am reading Bryan Peterson's Understanding Exposures. Great book, and I also found some answers about F numbers, that I have been wondering about for a while.
The diamteter of the aperture is the focal lenght divided by the F number.
50mm F2 = 25mm aperture diameter. This Sounds resonable.
How about 16mm F22? Aperture diameter of 0.72mm!!!
Can this be true?