I am looking to move into medium format and have been looking at Hasselblad's, but I haven't been able to find a precise breakdown of the differences between the 500c, 500cm, 501cm (is there a 501c??), 503cw (is there a 503cm?)?? From my research it appears that most 500cm packages come with an 80mm zeiss f2.8 lens on ebay. A breakdown of the lens line would also be helpful.