Superb corner-to-corner image quality from an ultra-wide-angle zoom
Tamron aims for the highest standards with the SP (Super Performance) lens series. And the new 15-30mm F/2.8 full-frame ultra-wide-angle zoom is a worthy addition.
This high-performance zoom lens equals the performance of fixed focal length lenses from 15mm to 30mm, an unprecedented achievement made possible by the development of its unique XGM (eXpanded Glass Molded Aspherical) lens element that effectively controls aberrations and enhances sharpness. In addition, the 15-30mm is the first zoom to combine such a wide range of coverage, a fast F/2.8 aperture, and to offer image stabilization, further proof of Tamron's commitment to innovation and excellence.
A large diameter XGM (eXpanded Glass Molded Aspherical) lens element is placed in the first lens group of a system that also includes several LD (Low Dispersion) elements in its 18-element, 13-group optical design. This combination effectively controls distortion and chromatic aberrations that typically affect wide-angle lenses.
XGM (eXpanded Glass Molded Aspherical):
The XGM (eXpanded Glass Molded Aspherical) lens element is capable of efficiently correcting aberrations in the angle of view that changes significantly with an ultra-wide-angle zoom lens. It has an especially significant impact on minimizing distortion and enhancing the sharpness of the image at its periphery.
Furthermore, the molded-glass manufacturing method allows the fabrication of a wider range of lens shapes than the composite aspherical lens method. Moreover, XGM also effectively controls aberrations and reduces total lens size. (Left：Conventional Molded-Glass Aspherical lens element, Right：XGM lens element)
Tamron's proprietary eBAND (Extended Bandwidth & Angular-Dependency) Coating suppresses tangential reflections, while a new generation of BBAR (Broad-Band Anti-Reflection) Coating has been optimized for ultra-wide angles of view. Together, they effectively correct ghosting and flare, yielding vivid images of extraordinary clarity.
Responding to the demand for a wide-angle lens suited for handheld shooting at slow shutter speeds, Tamron has created the world's first F/2.8 ultra-wide-angle zoom lens with image stabilization. The result is a lens able to capture sharp images even when shooting handheld under low light conditions.
This system employs three coils that move the optical compensation system electromagnetically via three ceramic ball bearings. It offers excellent stability and enables smooth movement with little friction. When equipping 15-30mm with VC, the design of the VC unit was optimized for a fast F/2.8 aperture ultra-wide-angle zoom lens.
The VC unit was made compact to prevent the body of the lens from becoming too large when equipping this fast F/2.8 aperture ultra-wide-angle zoom lens with the Vibration Compensation mechanism. Each VC unit is exclusively designed and optimized for each lens that incorporates this exclusive feature.
Since its large diameter and prominent convex profile prevents deployment of a protective filter, the front element of this lens has a fluorine coating that repels water and dirt, and makes it much easier to remove smudges as well.
Moisture-resistant construction helps prevent moisture from penetrating the lens.
The quiet high-torque USD motor ensures autofocusing with precision.
The lens offers the high levels of durability and operability expected in an SP lens, based on its exacting design specifications. Many of the components used in the lens' drive unit, such as those in the zoom and focus mechanisms, are made of metal (aluminum alloy). Their high level of manufacturing and assembly precision has resulted in a high-precision lens body that resists wear and deterioration over time. The zoom ring uses zoom mechanisms and cam arrangements refined over the course of Tamron's long history of high-power zoom lens development, providing smooth operation under variable torque. The focus ring employs a holding mechanism optimized for the USD (Ultrasonic Silent Drive), offering smooth torque during MF operation.
The integrated lens hood features a unique Tamron zoom-linked double-hood design which resists physical shocks such as accidental drops. It is designed to minimize damage to the lens.
This unique lens hood provides effective shading of the front lens surface over the entire zoom range to minimize flare. It utilizes the unique characteristics of the optical system in which the front lens group recedes as you zoom in from 15mm to 30mm.
Left: At focal length 15mm
Right: At focal length 30mm
By utilizing the unique characteristics of the optical system, the hood becomes relatively deeper and the shading effect improves when zooming. (right image)
Using state-of-the-art optical design, the lens provides advanced compensation for the optical aberrations common with ultra-wide-angle lenses, such as distortion and lateral chromatic aberration. In particular, lateral chromatic aberration is accurately corrected by using concave LD elements. This provides clear images with high resolution and enables high quality wide-angle images.
The high sharpness and contrast provided by this lens make it possible to accurately capture even the finest details of the subject. The superior imaging capability of the lens renders point light sources as sharp points, even in peripheral areas. This lens is therefore perfect for landscape, night, and astrophotography, all of which require high resolution across the entire frame.
This lens also takes into account the appearance of the areas at the corners of the frame. The clearly protruding front lens has a deep curvature designed to prevent peripheral light fall off. Even at its maximum aperture, there is very little observable or measurable peripheral light fall off.
Soft-focus backgrounds at wide-angle settings
Thanks to its large F/2.8 aperture, this lens lets you soften the foreground or background to dramatically emphasize the subject. And with a minimum focusing distance of 0.28m over its entire focal-length range, it can capture wide-macro effects.
The 9-blade diaphragm construction stays a nearly circular aperture even when stopped down two steps from its maximum aperture. It therefore maintains its ability to capture soft bokeh effects even when the aperture is stopped down.
At wide-angle focal length of 15mm, this lens enables photographers to capture an expansive perspective exceeding the angle of vision. At its long focal length of 30mm, it provides a semi-wide angle of view that is convenient for snapshots. By making the zoom magnification 2x while maintaining image quality, it is possible to provide both powerful capabilities in the ultra-wide-angle range and the natural expression of a semi-wide-angle, all in an eminently convenient package.
|Angle of View (diagonal)||
110゜32' - 71゜35' (for full-frame format)
85゜52' - 49゜54' (for APS-C format)
|Lens Construction||18 elements in 13 groups|
|Minimum Focus Distance||0.28m (11 in)|
|Max. Magnification Ratio||1:5 (at f= 30mm: MFD 0.28m)|
for Canon: 145mm (5.7 in)
for Nikon: 142.5mm (5.6 in)
for Canon: 1,100g (38.8 oz)
for Nikon: 1,100g (38.8 oz)
|Diaphragm Blade Number||9 (circular diaphragm blades)*2|
|Standard Accessories||Lens caps (push-on front, rear)|
|Hood||Integrated flower-shaped hood|
Canon, Nikon, Sony*3
Specifications, appearance, functionality, etc. may be changed without prior notice.
*1 Length is the distance from the front tip of the lens to the lens mount face.
*2 The circular diaphragm stays almost perfectly circular up to two stops down from maximum aperture.
*3 The Sony mount version does not include VC since Sony digital SLR bodies incorporate built-in image stabilization functionality.
For Canon, Nikon: January 30, 2015
For Sony: December 24, 2015
MTF (Modulation Transfer Function) curves describe to what extent the tested lens can faithfully reproduce contrast of the subject in images it captures.
The closer the 10 lp/mm (line pairs per millimeter) curve (the thick line for low frequency) in an MTF chart to "1" of the vertical axis (the higher up), the higher the contrast reproduction performance of the tested lens will be. The closer the 30 lp/mm curve (the thin line for high frequency) to "1" (the higher up), the higher the resolving power and thus the subjective sharpness of the lens will be.
Lens performance differs depending upon directions. Solid lines show performance in the sagittal (radial) direction while dotted lines indicate performance in the meridional (circumferential) direction. When sharp lenses capable of delivering uniform optical performance over the entire image field are tested, MTF charts show curves plotted in good balance.
Performance characteristics of photographic lenses cannot be expressed with only MTF charts. There are other factors that are expressed in different methods, such as taste of softness and degrees of compensation of various aberrations. But you can use MTF charts as a scale to measure lens performance.