Tamron AF 28-80mm f/3.5-5.6 Aspherical Lens for Pentax Digital SLR Cameras The Tamron AF28-80mm f3.5-f5.6 is a standard zoom lens with a wide to medium telephoto range of 28-80mm By using aspherical elements in the front optical group They also used strong, engineered plastic for the barrel, making the total lens body only 8.4 ounces The use of aspherical elements in the front group reduces the number of elements required A standard zoom lens from a wide 28mm to a medium telephoto range of 80mm