The optical construction (15 elements in 10 groups) uses four LD (Low Dispersion) lens elements to minimize axial chromatic aberrations that can occur with ultra-wide-angle zoom lenses. With two properly positioned GM (Glass Molded Aspherical) lenses, distortion and other aberration can be satisfactorily corrected as well. Being one of the smallest and lightest in its class and dedicated to high quality imaging, the engineers have paid particular attention to size. The lens has also been carefully designed to allow peripheral point image reproducibility and thereby facilitate a high degree of sharpness and contrast.
The Minimum Object Distance (MOD) for the entire zoom range is a short 0.28m (11 in), so background blurring is still possible when opening the aperture and approaching the subject close-up with this ultra-wide-angle zoom.
Advanced lens coating technology
Resistance to backlighting is extremely important for wide-angle lenses as they are often subjected to strong light sources. The Tamron 17-35mm F/2.8-4 Di OSD has a high level optical construction that repeatedly employs comprehensive ghosting analysis simulation. The BBAR (Broad-Band Anti-Reflection) Coating is highly effective in reducing reflection, allowing ghosting and flare throughout the entire zoom range to be controlled.
OSD enables both excellent AF & minimum drive noise
The AF drive system employs an OSD (Optimized Silent Drive) to ensure quiet operation. Through the innovative optimization of the system that includes AF system speed reduction gear, Tamron was able to greatly reduce the drive noise in comparison to conventional AF types with built-in DC motors. AF performance and speed have also been vastly improved. Thus, even if silence is required, AF can be employed without having to worry at all about noise creation. The Tamron 17-35mm F/2.8-4 Di OSD is able to provide superlative AF precision for exact focus even when shooting moving objects, as well as outstanding trackability.
Circular aperture to produce a smooth-edged bokeh
A 7-blade diaphragm is configured to retain a smooth, circular-shaped aperture opening even when stopped down by two stops from the wide-open aperture. This produces a smooth-edged bokeh in background light spots and avoids rugged aperture geometry.
Seals are located at the lens mount area and other critical locations to prevent infiltration of moisture and/or rain drops to provide Moisture-Resistant Construction. This feature affords an additional layer of protection when shooting outdoors under adverse weather conditions.
The surface of the front element is coated with a protective fluorine compound that has excellent water- and oil-repellent qualities. The front surface is easier to wipe clean and is less vulnerable to the damaging effects of dirt, dust, moisture or oily fingerprints, allowing for much easier maintenance. The coating also provides an enhanced level of durability, and will sustain its effectiveness for years.
Compatible with Tamron TAP-in Console (sold separately)
The Tamron 17-35mm F/2.8-4 Di OSD is compatible with the optional Tamron TAP-in Console, an optional accessory product that provides a USB connection to a personal computer, enabling users to easily update a lens’s firmware as well as customize features including fine adjustments to the AF.