I'm looking at getting one of these (since I can't afford a leica) and if I am correct, the only difference between the two is the viewfinder. The R3A has a 1:1, and the R2A has a .7x. Since I am not used to using rangefinders and have never owned one, I wanted to know why you would take one over the other? I seem to usually shoot with a 28mm on my Canon f-1 slr... Thanks for your help.