>>3389247mm = focal length in this case. Like 18-55mm kit lens or 200mm telephoto lens or a 50mm prime. That is the lens' focal length, not filter diameter or focal flange distance. Your kit lens is most likely the 18-55mm zoom.
>>3389245What brand is the film camera? I'm guessing uses an M42 screw mount? The flange focal distance (FFD) for a 1200d is EF-S and 44mm long. M42 mount FFD is 45.46mm long. A M42 to EOS (EF, EF-S) adapter ring is rather cheap, usually $10. If you get one, make sure there's no pin or tab on the lens that will lock into place and not come unlocked when the ring is put on. Some people have difficulty with that and spurge out like a retard. Also, if you tighten things down too hard and can't get the ring off, just mount the ring on the camera and unscrew it. That's the easy way to remove a ring that is stuck on filter threads or M42 screw mount. A lot of people don't seem to figure that out either.
