don't have an answer either to your question
you probably asking because you also have read (as did I) that the Chamonix bellows is not thick enough to be "IR proof"
the cheap solution to this problem, that I read is to purchase one of those Mylar emergency blankets. I am referring to those very thin blankets which are coated with a reflective coating on one side that is intended to keep you warm by reflecting the heat. Apparently if you drape this blanket over your bellows then it makes the bellows IR proof. I plan to try this but haven't yet. My Chamonix is the 45N1. They are wonderful light cameras.