The Tamron SP 11-18mm f/4.5-5.6 Di-II IF LD Di-II IF LD Aspherical lens is a super wide angle zoom lens and primarily designed for landscape or architecture photographers. Di-II technology provides an anti-reflection design technology to cope with stronger internal reflections created inside the mirror box of the camera or from light bouncing off the CCD or CMOS sensor. The internal focusing lens offers aspherical and LD elements to provide exceptional correction for any type of aberration while creating clear sharp images. The 11-18mm has seven diaphragm blades, lens construction of 15 elements in 12 groups, 0.25 meters minimum focusing distance, and 77mm filter thread. With the Tamron 11-18mm you will get precise autofocus and excellent performance and meet the needs of the photographer pursuing creativity.