From the Manufacturer
Reach out and grab distant detail, wildlife, and sports action with this amazing 11X extended range wide-to-super tele zoom that covers both full-frame and consumer DSLR (APS-C) formats allowing you to focus down to an incredible 0.49m(19.3") (1:2.9) for breathtaking close-ups. If there’s any compact zoom that does it all on digital and film SLRs, this is it.
AF28-300mm F/3.5-6.3 XR Di LD Aspherical (IF) Macro Highlights
Maintaining the high performance of the previous model, Tamron's 28-300mm zoom lens now features our "Di" design, making it the ideal lens for use with both digital and film cameras. The "Di" design is achieved by applying a new optical design to its coated surfaces, and by further enhancing our already stringent quality control system. Whether you shoot film or digital, the lens provides high image quality for both platforms. When used with APS-C size digital SLR cameras, the lens provides an angle of view equivalent to approximately 44-465mm, covering the standard to ultra telephoto range with no sacrifice of quality or aperture range.
Low Dispersion (LD)
Low 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.)
Anomalous Dispersion (AD) for Better Color Correction
Anomalous dispersion (AD) glass is a special type of optical glass that is used to achieve more precise control of chromatic aberrations, thereby enhancing overall imaging performance. Glass of this type provides an abnormally large partial dispersion ratio (amount of diffraction) for light of specific wavelength ranges (colors) within the visible spectrum. By combining AD glass having these special characteristics with elements made of normal glass having different dispersion characteristics, it is possible to control the dispersion factors of a specific wavelength. This enhanced level of control results in much lower levels of on-axis (central) chromatic aberration for telephoto lenses (or zooms used at tele-photo settings) and a significant reduction of lateral (peripheral) chromatic aber-ration for wide-angle lenses (or zooms used at wide-angle settings.)
Extra Refractive Index (XR) glass can bend light rays at steeper angles, thereby decreasing the physical length of the lens while enhancing imaging performance by minimizing optical aberrations. This has allowed Tamron to develop a line of shorter, smaller-diameter, lighter lenses without sacrificing lens speed, and actually upgrading image quality compared to older designs. XR glass is costlier than conventional glass but it yields enhanced optical power distribution, making possible many of the outstanding and innovative lens designs that bear the XR designation. XR glass, with its superior light-bending power, makes it possible to design a short-barrel lens with the same light-gathering ability (aperture value) as a long-barrel lens—even with a smaller lens diameter. By using this principle Tamron has been able to shorten the length of the entire optical system and produce lighter, more compact lenses of the same speed, and also to provide greater zoom ranges in lenses that are much more convenient to carry by hand.
Aspherical Elements (ASL) Provide the Ultimate in Image Quality and Compactness)
Tamron uses several hybrid aspherical lens elements in many lenses bearing the Aspherical designation. These innovative optics allow us to achieve the ultimate in image quality, and at the same time produce lenses that offer remarkable zoom ranges in extraordinarily compact packages. By perfecting theses cutting-edge advances for series production, Tamron has advanced the state of optical design, and virtually eliminated spherical aberration and image distortion from the high-power-zoom series.Through the effective application of Hybrid Aspherical Technology, one lens elemen tcan take the place of multiple elements without compromising performance. This is what allows us to produce remarkably compact long-range lenses that deliver a uniformly high level of image quality at all focal lengths and apertures.
Internal Focus (IF)
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.
Zoom Lock (ZL)
Another original Tamron mechanical engineering concept is the Zoom Lock (ZL), a simple convenience feature that prevents undesired extension of the lens barrel when carrying the camera/lens unit on a neck strap.