Ken, While others may offer some additional notes here is what I know. The Rolleiflex 2.8F and 3.5F of 1958 were the first Rolleiflex TLRs with a coupled exposure meter. There were actually 3 variations on this model before 1960. The first model had a newly developed Compur shutter and was limited to production of 20,000 units. The next 11,000 units were a design with older style shutter and aperture controls and had a certain stiffness that many users criticized that forced F & H to change to a third version with a smooth operating bevel-geared differential. The 3.5 version of this model also received a newly designed Planar lens of six elements, followed by a new Schneider 3.5 Xenotar with six elements. This was allegedly to improve the resolving power since F & H were of the opinion that the older style 5-element 3.5 lenses did not live up to expectations. The 2.8 Zeiss and Schneider lenses remained unchanged. This was the last of the famous TLRs to be produced from 1960 through 1981. Kodak introduced 220 film in 1965 so the 12/14 version would have had to come after that, precisely when I am not sure, but I know others will of course provide you with more detail whether you want it or not. Carlos, Jerry, your turn. :-) Peter K