The TC has an index mark at the top of the aperture read-out bar on the right side of the finder. This is used for stop down metering with lenses which do not couple with the camera's meter. T Mount lenses and lenses used with the Konica adapters work with this mark. Adapters were made for using Konica F mount lenses, M42 (Praktica/Pentax Screw), Exakta/Topcon and Nikon F. All of these lenses will have correct infinity focus. In order to meter properly with an M42 lens using the adapter you will need an M42 lens which has the A/M (Auto/Manual) switch. You need to set the lens to M. As you close down the lens the fider will darken and the meter needle will move. It helps to at least estimate the exposure before metering so you will not have to go back and constantly change the shutter speed. There were some M42 lenses which have auto diaphragm operation (with an M42 camera body) but which lack an A/M switch. These lenses will only be usable wide open with the TC and adapter. If you have reason to believe that the camera is not working properly you can contact Greg Weber at 402-721-3873 or gweber@webercamera.com. He services Konica equipment.