The sony vclecu2 ultra wide converter is for use with the sony e16mm f28 and e20mm f28 e mount lenses the converter screws onto the end of the lens to widen its perspective so that you can capture the bigger picture and fit more in your shots when mounted onto a sony e16mm f28 lens the focal length changes to 12mm and on a sony e20mm its 16mm this ultra wide converter is the ideal accessory for existing sony e mount 16mm and 20mm users looking to explore landscape photography in more dep