The F Ratio is the ratio between the focal length f and the diameter d of the lens. Strangely, f/6 means that f/d = 6

Fast OpticsEdit

A small F Ratio corresponds to fast optics because d > f which means that more light will pass through the apperture, reducing the time it takes to make an image.

Slow OpticsEdit

A large F Ratio corresponds to slow optics because f > d which means that the same image will be spread across greater area. To get the same amount of photons per area, we need more exposure time.