This is achieved with the use of a small aperture ring lug on the back of the lens. Dust is out of the photographic plane and simply will not affect a photograph. No oil on blades. Aperture ring smooth in operation.
Olympus OM fit Sigma 70-210 f4.5 lens. Olympus OM fit Vivitar 28mm f2.8 lens. OM to Fuji X Adapter. Half leather carry case for the Sigma lens. Fujifilm X-Pro1. Fujifilm X-M1. Fujifilm X-E3. Fujifilm X-E2s.