I am thinking about getting a 501CM and need to know which components I would need at a minumum to be up and running. I want to travel with this outfit and so I don't want to bulk it up too much. From what I have seen so far I would want to get the Acute Matte or Acute Matte D focusing screen (any opinions about a Beattie screen as a less expensive alternative?). I would want to get a standard angle lens (80mm), and two backs. Initially I would be using this outdoors for landscapes and portraits. Later on I would start adding lenses. I do have a Metz 145 CL-45. Is this compatible? What else do I need? In looking at KEH I see they have a lot of different backs and I am not familiar with the nomenclature. I assume the A12 backs are for 120 film with 12 exposures and the A24 for 220 film with 24 exposures. Is that correct? So far my KEH shopping cart for a 501CM body with fast crank, WLF , Acute Matte D, A12 back, 80mm lens comes to right around $1,300.00.