Pixco Adjustable Aperture Speed Booster Optical Glass Full Manual Operation Focal Reducer Durable Mental Lens Adapter Canon EF Lens to Micro Four Thirds M4/3 Micro 4/3 Camera Effect: It converts fullframe lenses into APS-C lenses. The advantage is to get the fullfame field of view onto the APS-C sensor. Full manual operation, manual focus, manual iris adjustment can be achieved with body manual exposure, aperture priority exposure, combined infinite focus. Built-In aperture control foradjustingthe amount of light let into your camera. Increase exposure to 1 stop, and you can use faster shutter speed to shoot an image. Pixco is registered Trademark by the United States