F-Stop Explained

I’ve been asked to explain ƒ-stop countless times over the years. This video is almost 15 minutes long, but if you really want to know how ƒ-stop numbers work and what the numbers mean, this is a good start. The first aha moment happens about 10 minutes in, but in order to have the aha, you have to watch the whole thing.

via: Stellar Interesting