NEW 2 me today! 12". Anybody have any info? History? Who was beach? There are concentric rings in the rear group on what otherwide appears to be an ordinary Tessar type. How and why do they work? How is it a multifocal? Anxious to learn about my new toy! Going upstairs to look at my "wine bottle" through the lens. Nice clean glass and in a SHUTTER for once!! Who me? Excited? About an old crusty lens? NAW.... .................------------------..........................--------------------........ 10 minutes later; OK. Looked through it. I don't get it?? It looks for all the world exactly like an ordinary uncoated 12" Tessar of which I have quite a few. In fact the barrels are identical to my 12" Velostigmat. I mean interchangeable. They're the same. So the only difference is the magic swirlies in the rear group?? And the weird descending numbers where the aperture scale would normally be. Like 11.7 wide open, then 11, 10, 9, - down to 4 where it would be at about f45. What's that all about.