i am about to put on ebay some old stuff that I started learning photography on. most of it was given to me by my mom or my grandma, and I have a couple filters that I'm not sure what they even are. anybody know what these are? 1: Kenko PL Ø49 JAPAN (i assume the Ø49 is 49 mm diam) 2: PRO 49Ø 81B JAPAN 3: Kenko Px2 Ø49 (doubler?) 4: Kenko LBW4 Ø49 I also have a packet of 3 close-up lenses, but they are marked No. 1, No. 2, and No. 4. what do the numbers mean? thanks!