I've only had one lense since I bought my SF-10 in 2000: an F 35-70/3.5-4.5. I ordered an M 75-150/4 from Adorama and it showed up last week. I was getting rather frustrated with the new lense because I could only focus it by turning what I thought was the zoom ring, and I couldn't find the narrow focusing ring that I was used to. I just realized this morning that the wide (***wide***) ring is the focusing ring, and you don't twist anything to zoom in/out; you just slide the focusing ring in/out. :-)
Seeing as this is the first lense I've bought independent of a body, I don't have much frame of reference to evaluate this new purchase, but I had no problems with Adorama, and the only fault I can find with the lense is a small scratch in the black lacquer on the lense hood. -Rich Worcester, MA, USA