Hello, my first post to the forum after many months of lurking and learning I recently purchased a circular polarizer (B50) from KEH for my Hasselblad 150mm f/4 Sonnar. I'm attempting to verify the stop loss so that I can compensate either on the lens or light meter. Would anyone have information on how to figure this out? Does the '-1' mean one stop of light is lost? Photo of the filter is below.