I have inherited quite a bit of camera equipment from my grandfather. One of the items is a mamyia/sekor 500 DTL with several lenses. One of the lenses is a Sears brand 28mm f:2.8. Does anyone know who made these lenses? I have read that Pentax made some of the Sears brand lenses, but I have not been able to verify this on the web. I have not had a chance to use the lens yet to find out of it is any good.