Xenon 40mm f/1.9

Notes and sources

Robot M26 screw-mount lens only; the rangefinder-coupled Royal bayonet lens is not included. The measured heavy barrel (216g, 0.7m nearest focus) and lightweight five-blade barrel (124g, 0.5m nearest focus) remain separate Versions. These are specimen measurements, not asserted production-wide tolerances. A further exact-lens review documents a 15-blade, 0.7m-focus specimen and a 6-element/5-group construction; that iris count and formula have not been copied into every heavy-barrel or later Version without a firm generation match. The five-blade specification must not be overwritten by the older iris count. Exact filter-thread standards and production boundaries remain unverified.