LEICA SUMMICRON-M 50mm f/2 (1979-1994 version, 39mm filters, separate clip-on A42 hood, 6.7 oz./195g). enlarge.
Both these versions share identical optics. I prefer the earlier version with the clip-on hood. Its hood works better, it doesn't keep collapsing as does the push-in/pull-out hood of the newer version, and it weighs less than the newer versions.
Donc 42 ç zst pour le bouchon parsoleil et 39 si on met un bouchon direct sur l optique