Hi, I have seen many Patek's watches both from shops and magazines. I pretty much know the regular production models but have no clue whatsoever r/e their older models especially calatrava. There seems to be so many models (old and new) of Calatrava? Can any Patek expert share something for my knowledge? I mean, how to learn more about Patek and how to decide which to buy for your first piece? I also notice there are not too many SS models (Nautilus, Aquanaut, Neptune), are they rare? Thanks in advance.