Internal Focusing (IF) System

Internal focusing (IF) 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.

Low Dispersion (LD) Glass for Greater Lens Sharpness

Low dispersion (LD) glass elements in a lens help reduce chromatic aberration; the tendency of light of different colours to come to different points of focus at the image plane. Chromatic aberration reduces the sharpness of an image, but glass with an extremely low dispersion index, has less of a tendency to separate (defract) a ray of light into a rainbow of colours.
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.)

VXD (Voice-coil eXtreme-torque Drive)

VXD is first-ever linear motor focus mechanism for stunningly fast and accurate auto-focusing. Focus tracking has also been vastly improved during sports and racing photography. This ensures that those powerful moments are never missed, whether shooting still photos or video. With the excellent quietness that is characteristic of linear motor systems, the AF is ideal for shooting in low-noise environments.

ZL (Zoom Lock) Feature

The original Tamron mechanical engineering concept is ZL, a simple convenience feature that prevents undesired extension (creep) of the lens barrel when carrying the camera/lens unit on a neck strap. This enhances responsiveness in the field and helps protect the lens.