I only see sunny 16 as a guide point for exposure, generally don't use f16. But it's all simple math, ASA 100 = f16+1/125 or f11+1/250 or f8+1/500. If overcast f8+1/125 or f11+1/60 or f16+1/30, and so on. I call it all "sunny 16" because the starting point is ASA=shutter speed + f16 for mid day sun. If you really just stick to f16 and sunny days, then yes it is rather limiting.