1.3 inch (18 mm) equivalent, 10 lenses in 8 groups and an inner focus that does not change length when focusing adjusted. It maintains high resolution from the center to the peripheral, and the thorough reduction of distortion aberration can be used for a wide range of scenery, architecture, and shooting in narrow rooms, etc.Aluminum alloy exterior for a high grade appearance.The aperture ring has a stepless aperture with no click sensation, so you can enjoy watching videos.