I know of only one brand, the Rolleiflex 200F, 3001 and 3003. The backs were rectangle units, like small Hasselblad backs. The cameras did not sell well in the 1980s in the US market. Check out the article on Cameraquest. I recall reading that they suffered from electronic problems, and the NiCd battery packs have probably failed. Is anyone here on APUG using one of these Rolleis?