Lens Specifications
Main Features:
Fast, wide-angle to medium telephoto zoom lens with a constant aperture of f/2.8.
Three glass-molded aspherical lenses and one hybrid aspherical lens to control chromatic aberrations while enhancing sharpness and contrast.
Three low-dispersion (LD) lens elements for increased sharpness.
Two extra-refractive index (XR) lens elements for reduced aberrations and better imaging performance.
Tamron’s Ultrasonic Silent Drive (USD) provides near-silent high-speed auto focus with superb accuracy.
AF/MF focus mode switch allows changing between manual and auto focus operation.
Rugged construction with professional-grade dust and moisture resistance.
Read more: http://photographylife.com/reviews/tamron-24-70mm-f2-8#ixzz2yCRnyVCa