From 100% - 0.8% Reflectance is seven stops. I guess technically the range could be infinite as you would never reach zero if you are always dividing by 2.
Originally Posted by Bill Burk
Remember, the use of Reflectance in relation to luminance usually involves a Lambertain surface which is a perfect diffuser. 100% Reflectance doesn't mean 100% reflection - (illuminance x reflectance) / pi = luminance.
Scenes with Reflectances of 100% and above incorporate non Lambertain surfaces and specular reflections. There's also relative Reflectance like when shooting a scene with multiple lighting conditions, like the cave and the beach. You have a a normal scene in bright sunlight and then a normal scene in dark shadows. If you are shooting the inside of the cave, the exterior scene will appear to have Reflectances easily over 100%.
However, that still doesn't answer of Zone VIII being at 144% when Zone V is considered to be metered at 18% gray.