First of all I would like to say hi from Perth Western Australia. Photography has been a passion of mine for many years, off and on with various work committment! I learned to shoot film with a manual camera and although I have quite a good digital camera I find myself going back to my trusty Canon AE1. Which is how and why I found this fabulous site. I'm considering buying a medium format camera and so far like Hasselblad as they don't appear as bulky and seem more portable. I also like the square format. Having said that i'm not sure what some of the differences are between certain models. The model i'm considering is the 500 series. What is the difference between 500, 501 or 503?