The ef s 10 18 mm f45 56 is stm lens combines optical excellence with cutting edge performance providing an ultra wide angle of view in a compact portable package perfect for eos cameras with an aps c sensor it has a 4 group optical zoom system and includes a large diameter element an aspherical lens element a ud lens element and enhanced lens coatings for high contrast high resolution images with minimal glare and aberration a circular 7 blade aperture helps ensure fine background b