Pixco Pro Focusing Infinity Speed Booster Focal Reducer with Optical Glass Adapter Lens Turbo M42 Mount Lens to Micro four thirds M4/3 Max. f-stop pass through: 1.4 Optical design (lenses / groups): 4/3 Focal length extension: 0.7x, Image diameter (mm): 28.5, Bayonet front: 135 full frame lens, Bayonet back: Sony NEX / Fuji X / Micro 4/3 Full manual operation, manual focus, manual iris adjustment can be achieved with body manual exposure, aperture priority exposure, combined infinite focus. Compatible with: M42 Lens, Micro Four Thirds 4/3 Camera.