> 139's are easy to find on eBay but almost always require extensive cleaning, lube, and adjustment. Older serial numbers are a poor gamble. I had the great good fortune to find a 139 with serial number above 200000 which appeared to be new in the box! I also recently had my own original 139 cleaned and re-foamed. I've had it for 25 years, and it works perfectly. On another tack, the camera I had the most fun with using the 45 Tessar is the AX. I put the anniversary Tessar, which is MM, on it and used it as an autofocus, programmed-exposure point-and-shoot. It has to be the world's largest point-and-shoot! But it worked beautifully. --Gary