The EC were designed for the DX3, the camera that bankrupted AiC, the American company that owned Miranda and Soligor. Years, maybe twenty I had an Email exchange with the retired owner of Brookland Camera who retailed Miranda, He, don't recall his name, wrote that the EC lens were built by Miranda one of the reason AiC aquired so much debt and pushed the release of the Dx3 despite it's shortcomings. The Dx3 does not have auto exposure, spot meter or interchangeable viewfinders, but there were plans for a motor drive. Takes 4 batteries, came with a case for batteries when the camera was in use and the manual advises the owner to carry spare batteries. I have one, it worked for a few weeks, not a bad camera, other than the battery situation nothing stands out. The 50 1.7 E.C works fine on my EE2, sharp good coatings.