From the Manufacturer
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This ground-breaking high-speed mid-range zoom is prized by pros
and serious shooters for its fast F/2.8 constant aperture,
evenness of illumination, and its outstanding imaging
performance, and by all photographers for its compact size and
reasonable weight that make it feel like an ordinary standard
zoom. These admirable characteristics have been achieved by the
use of special XR and LD glass, the efficient use of aspherical
elements, and non-rotating internal-focus (IF) design. This
remarkable zoom lens also focuses down to 0.33m (13”) (1:3.9
magnification) at all focal lengths for satisfying close-up
performance and is compatible with APS-C and full-frame-format
SLRs. Not surprisingly it is widely accled as a classic.
Worlds smallest & lightest lens
The most compact and lightest in the history of fast zoom
lenses. Thanks to the revolutionary downsizing "XR" technology
employed by Tamron in the development of high-power zoom lenses
such as the 28-200mm and 28-300mm, the dramatic compactness that
makes this lens the world's smallest and lightest is achieved.
Its compactness makes it look and feel like an ordinary standard
zoom lens, yet the versatility that a fast constant maximum
aperture offers will definitely reshape your photographic
horizons.
SP AF28-75mm F/2.8 XR Di Features
Digitally Integrated (DI) Lenses for the Best Imaging
Performance
Di (Digitally Integrated Design) is a Tamron designation that
applies to lenses that have been optimized 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.
Low Dispersion (LD) Glass for Greater Lens Sharpness
Low Dispersion (LD) glass reduces chromatic aberration 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.)
Super Performance (SP) for Discriminating Shooters
Tamron SP (Super Performance) series is a line of
ultra-high-performance lenses designed and manufactured to the
exacting specifications demanded by professionals and others who
require the highest possible image quality. In creating SP lenses
Tamron’s optical designers put their foremost priority on
achieving superior performance parameters—they are all designed
to a higher standard with little regard for cost constraints. As
a result, Tamron lenses bearing the SP designation feature
impressive and innovative designs that have established an
enviable reputation for excellence among those knowledgeable
photographers that demand the very best.
Extra Refractive Index Glass (XR)
Special glass for better performance and more compact lens
designs 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.
Internal Focusing (IF) System
Internal 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.
Aspherical Lens Elements (ASL)
Aspherical Lens Element 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 element can 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.
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.
- Tamron 28-75mm f/2.8 XR Di LD SP AF Lens - Pentax.
