From the ManufacturerThe acclaimed Tamron 18-270mm VC ultra zoom for APS-C format DSLRs has reached an astonishing new level of compactness, performance, and speed with the addition of PZD (Piezo Drive), an innovative ultrasonic autofocus motor based on an advanced piezoelectric design. The result is a lens that's considerably lighter, and noticeably shorter and slimmer (filter diameter: 62mm) than any previous lens in its class, and provides faster, quieter auto-focusing.Signature features that have made this amazingly versatile lens the world standard in its class have been retained. They include a 28-419mm equivalent (15X) zoom range, an improved, lightweight, compact Vibration Compensation (VC) system, macro focusing to 0.49m (19.3 inches) throughout, and, of course, superlative imaging performance.Piezo Drive (PZD) Ultrasonic Autofocus MotorUltrasonic motors are divided into two categories depending on the principle that generates the energy to move the drive: traveling wave motors and standing wave motors. Traveling wave motors include the ring type ultrasonic motor used in the recently launched 70-300mm F/4-5.6 VC USD as well as other lenses, but this lens employs a newer technology, the PZD (Piezo Drive), which functions on the standing wave principle.A standing wave ultrasonic motor utilizes high-frequency voltage to extend and turn the piezoelectric (piezoceramic) element, thus moving the entire element in a standing wave movement. The metal tip is the contact point of the element to the rotor, and moves in an elliptic motion from the swiveling motion of the moving element, and the friction from this motion turns the rotor. Standing wave ultrasonic motors have the distinct advantage of being smaller than their traveling wave counterparts, and therefore allow a more compact SLR lens size.Di IILenses are designed for exclusive use on digital cameras with smaller-size imagers and inherit all of the benefits of our Di products. These lenses are not designed for conventional cameras and digital cameras with image sensors larger than 24mm x 16mm.15x Zoom RatioThis lens covers an extremely broad range of focal lengths, from an extra-wide 18mm length to a telephoto 270mm length (the 35mm equivalent of 28mm to 419mm). The resulting 15x zoom ratio is the world's largest, representing a wide cross section of Tamron high-power zoom design technologies. Plus, the vibration compensation works throughout the entire zoom range, giving you the freedom to create a wide variety of images. The lens lets users capture once-in-a-lifetime panoramic landscape images or close-up pictures of children smiling, all without getting too close to the subject or changing lenses. Other details include a macro magnification range of 1:3.5, a minimum focusing distance of 19.3 inches, and a 72mm filter diameter. The lens, which measures 3.1 inches in diameter and 3.9 inches long, carries a six-year warranty.Vibration Compensation (VC)Shake can ruin your photos, particularly when taking telephoto shots or shooting in low light conditions.Simply flip the VC switch on and you'll notice the difference immediately. VC delivers blur free - handheld images for incredible results VC mechanism employs a three-coil system Lens element compensates for vibration using 3-steel balls (making movement quiet & smooth) Exceptional images at slower shutter speeds - reduces the need for a tripod Bring out contrast to motion & stillness Eliminate the need to shoot with a FlashLow Dispersion (LD) Glass for Greater Lens SharpnessLow dispersion (LD) glass elements in a lens help reduce chromatic aberration; the tendency of light of different colors to come to different points of focus at the image plane. Chromatic aberration reduces the sharpness of an image, but glass with an extremely lowdispersion index, has less of a tendency to separate (defract) a ray of light into a rainbow of colors. This characteristic allows the lens designer to effectively compensate for chromatic aberration at the center of the field (on axis), a particular problem at long focal lengths (the telephoto end of the zoom range), and for lateral chromatic aberration (towards the edges of the field) that often occurs at short focal lengths (the wide-angle end of the zoom range.)Internal Focusing (IF) SystemInternal focusing provides numerous practical benefits to photographers including a non-rotating front filter ring that facilitates the positioning of polarizing and graduated filters, and more predictable handling because the lens length does not change during focusing. Even more important, Tamron’s Internal Focusing (IF) system provides a much closer minimum focusing distance (MFD) throughout its entire focusing range. In addition, IF improves optical performance by minimizing illumination loss at the corners of the image field, and helps to suppress other aberrations that become more troublesome at different focusing positions.Zoom Lock (ZL)Another orig