"16 stops" means a ratio of 2^16, so in this case a 16-stop filter is a filter that allows 1/2^16 = 0.0015% of the light through. This is presumably "neutral de

"16 stops" means a ratio of 2^16, so in this case a 16-stop filter is a filter that allows 1/2^16 = 0.0015% of the light through. This is presumably "neutral density" that blocks all colours of light equally and has no other effect.