AF28-300mm F/3.5-6.3 XR Di VC
The cutting-edge 18-element 13-group design of the 28-300mm VC lens incorporates XR (extra refractive-index), LD (low dispersion) and AD (anomalous dispersion) glass as well as hybrid and glass molded aspherical elements to deliver exquisite sharpness and colour correction over its extended range. The Di (Digitally Integrated) designation is Tamron's assurance of optimal digital and analogue imaging performance. Capturing razor-sharp handheld images just got a whole lot easier and better.
This lens covers a tremendous range of focal lengths – on a full-size format SLR camera, the range is from 28mm wideangle to 300mm ultra-telephoto. When mounted on a DSLR with an APS-C sized imager, it covers a 43mm wide angle to 465mm equivalent ultra-telephoto* (full-size format equivalent, in a diagonal angle of view of 5°20').
* The ratio used by Tamron to convert from full-size format to APS-C focal length is 1.55x
VC (Vibration Compensation) mechanism reduces lens shake
The proprietary VC (Vibration Compensation) mechanism developed by Tamron features a three-coil system using three pairs of driving coils and steel balls around the compensator group of the lens’ optical system. Since the compensator lenses are supported with rolling friction of the balls, the response performance is enhanced and the construction is simple, which results in the compactness of the lens. The lens incorporate a highly accurate gyro sensor for detecting hand-shake, which, combined with a 32-bit RISC CPU, offers comfortable anti-vibration effects.
Outstanding design combines high zoom power, VC mechanism and compact size
The AF28-300mm F/3.5-6.5 XR Di VC integrates optical technologies that Tamron has accumulated as the pioneer and leader of high power zoom lenses in order to realize the desired compactness even while incorporating the VC mechanism. The optical system uses a number of lens elements made from special optical glass materials including XR (high refraction index) glass elements, GM (glass-molded aspherical lens) elements, hybrid aspherical elements, LD (low dispersion) glass elements to compensate for on-axis and lateral chromatic aberrations and AD (anomalous dispersion) glass element. The lens offers high contrast, high resolution performance and flatness of the image field as a one-does-it-all zoom lens designed to match the characteristics of DSLR cameras.
Revolutionary close-up distance of 0.49m throughout the zoom range provides 1:3 macro magnification
The AF28-300mm F/3.5-6.3 XR Di VC LD MACRO boasts an MFD (minimum focusing distance) of 0.49m (19.3″) over the entire zoom range, a top-class closing focusing capability among high power zoom lenses for full-size format SLR cameras, which provides the remarkable maximum macro magnification ratio of 1:3 at the 300mm telephoto end.
Internal surface coatings minimise ghosting and flare
The use of internal surface coatings (i.e. multiple-layer coatings on cemented surfaces of plural elements) and multiple-layer coatings prevent reflections from lens surfaces, ghosting and flare due to reflections that occur when light enters through the front element. Reflections caused by the imaging sensor itself in the mirror box are reduced to the absolute minimum.
Ultra-high zoom power in a lightweight, compact design thanks to new mechanical devices
Tamron has reviewed the roles that respective barrel parts play in order to achieve the high power, compactness and light weight. As a result, dimensional increases are confined to a mere 17.8mm (0.7″) in overall length and about 5mm (0.2″) in diameter, when compared with the previous model of AF28-300mm – despite the incorporation of the VC mechanism.
Useful when carrying the lens/camera over the shoulder
Another original Tamron mechanical engineering concept is the zoom-lock mechanism, which prevents the weight of the lens barrel from extending the lens when carried on the camera pointing downward. This eliminates the danger of accidentally knocking the lens while walking around and enhances responsiveness in the field. Simply zoom the lens out to its widest focal length and use the sliding zoom-lock switch to lock the barrel in place.
Flower-shaped hood is supplied with the lens to shield stray light
Included as a standard accessory, the flower-shaped hood matches the rectangular shape of the image sensor to most effectively block the interference of superfluous light rays entering from outside the borders of the image area, helping to ensure sharp, clear, flare-free images with crisp detail in the shadow areas.
Sharpens edges by reducing ‘colour fringing’
Chromatic aberration occurs when a lens element refracts different wavelengths of a ray of light – its rainbow colours – at very slightly different angles. This results in the ‘colour fringing’ that reduces the sharpness of an image. LD elements are made from special glass materials with extremely low dispersion indices (i.e. the refraction of a ray of light into rainbow colours is extremely narrow). Thus they effectively compensate for chromatic aberration at the centre of the field (on axis), a particular problem at long focal lengths (the telephoto end of the zoom range), and for lateral chromatic aberration (toward the edges of the field) that often occurs at short (wideangle) focal lengths.
Although costly, LD glass materials result in clear, vivid image quality.
Focusing elements inside the optical design make for better handling
In many lenses, the front elements move back and forth to alter the focus distance. With an internal focusing (IF) mechanism, the focusing elements are inside the optical design. Because the front lens elements remain static, the lens’ actual length does not change. This provides several benefits both to the image and during photography:
- The barrel is not subject to stray light entering from external helicoids that can adversely affect image quality
- A non-rotating front filter thread makes it easier to use filters such as graduated filters and polarisers
- A flower-shaped lens hood will remain in the correct position to most effectively shield the lens from stray light
- Better balance and more predictable handling because the lens length does not change during focusing
- Generally, a much closer minimum focusing distance throughout the zoom range
- Improved optical performance by minimising loss of illumination at the corners of the image field (vignetting)
- Suppression of other aberrations that become more troublesome at different focusing positions.
Integrated focus cam optimises internal focusing
Tamron’s Integrated Focus Cam is a precision mechanical component that optimises the co-ordinated movement of the Internal Focusing (IF) system with the Multiple Cam Zoom Mechanism. This ingenious mechanism ensures accurate and seamless positioning of all the internal elements within the lens and coordinates them with the external zoom and focus controls.
Compensates for camera blur on long shutter speeds – for sharp images in much less light
Tamron’s unique VC mechanism uses a proprietary actuator and algorithms to deliver an extremely stable viewfinder image with excellent tracking. The mechanism employs a tri-axial system in which three driving coils move internal optical components within the VC lens electromagnetically, based on signals originating from three steel ball bearings. The VC lens elements are held in place only by contact with the steel balls, achieving smooth movement with minimal friction. The simplicity of this mechanical structure is also one of the secrets of Tamron’s compact lens sizes.
Controls the dispersion of specific wavelengths of light
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 (colours) 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 much lower levels of on-axis (central) chromatic aberration for telephoto lenses (or zooms used at telephoto settings) and a significant reduction of lateral (peripheral) chromatic aberration for wide-angle lenses (or zooms used at wideangle settings).
Like LD glass, AD glass material is costly but provides clear, vivid image quality
Far superior image quality – while reducing lens size and weight
Tamron uses several hybrid aspherical lens elements in its lenses bearing the Aspherical designation. The benefits are two-fold: first, their non-spherical shapes virtually eliminate spherical aberration and image distortion. Second, as one hybrid aspherical lens element can take the place of multiple elements without compromising performance, they allow the lens to be much more compact.
As a result, these innovative optics have played a crucial role in delivering uniformly high image quality across all apertures and focal lengths of extraordinarily compact ultra-zoom lenses.
Extra Refractive Index
More compact lenses with superior image quality
XR (Extra Refractive Index) glass can bend light rays at steeper angles, thereby decreasing the physical length of the lens while enhancing imaging performance by minimising optical aberrations. With its superior light-bending power, XR glass 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 and hand-hold.
XR glass is costlier than conventional glass but it yields enhanced optical power distribution, making the innovative XR lens designs possible.
* Values given are for Nikon AF-D models.
Optimal image quality on both digital and film SLRs
Di is a Tamron designation that applies to lenses that have been optimised for digital capture using advanced multi-coating techniques and optical designs that assure excellent image quality across the entire picture field. Because of these characteristics, Di lenses provide outstanding performance on cameras with full-frame and APS-C format sensors as well as on 35mm film.
Tamron’s Di range
- SP AF28-75mm F/2.8 XR (Model A09)
- SP 24-70mm Di VC USD (Model A007)
- AF28-300mm F3.5-6.3 XR (Model A061)
- AF28-300mm F3.5-6.3 XR VC (Model A20)
- SP AF70-200mm F/2.8 (Model A001)
- SP AF70-300mm F/4-5.6 VC USD (Model A005)
- AF70-300mm F/4-5.6 (Model A17)
- SP AF200-500mm F/5-6.3 (Model A08)
- SP AF90mm F/2.8 Macro (Model 272E)
- SP AF180mm F/3.5 Macro (Model B01)