The Industar-69 (Индуста́р-69) is a strange but beguiling beast. Originally designed for the Chaika (Чайка) camera, it wasn’t really meant to be used with other cameras. The original Chaika’s lens wasn’t removable; on later models it was affixed with an M39 thread, apparently with the intent that photographers could mount it on an enlarger for printmaking. This intent might be apocryphal, I can’t properly tell. There’s not a lot of primary sources of information on this lens out there on the interwebs that I can find, only a handful of people repeating the same information.