I was the lucky bidder on a couple of lenses. One of which was an Auto H 50/2. It came with a M ring attached and in a presentation case. I can only seem to find information regarding the M ring + the 55mm lens. From what I gather the 27.5mm ring attached to a 55mm lens produces a macro 1:1 ratio. so true or false? if 55 mm + 27.5 = 1:1 then 50mm + 27.5 = <1:1 (1:-.975) if the answer is false...please explain.