The original rubber hood of this lens is very keen on breaking, especially after 30 years. The thread size on the lens is the so-called “Series 5.5″, i.e. 39×0.75mm. This is a very unusual thread size, and hoods with this size haven’t been made for a long time, or at least they’re nowhere to be found. Many people tried to use adapter rings and other home-brewed solutions to solve the issue. Eventually someone came up with the best solution on ebay: New Metal Hood for Leica Summicron-C (S5.5) 40mm f/2.0. I bought it and it does a great job.
Posted from Padua, Veneto, Italy.
A hard working wasp in the big garden of the Internet