The pentax da 50 135mm f28 ed if telephoto zoom lens is designed for exclusive use with pentax digital slr cameras delivering the highest level of ultimate optical image quality with aspherical elements special optical glass elements and original lens coatings this lens is superior in terms of contrast clarity and edge to edge sharpness the 50 135mm features tightly sealed weather resistant and dust resistant construction to enhance durability for use in rain or dusty conditions a n