With its wide zoom range, this lens has a focal range equivalent to 25.5-105mm on a 35mm lens. Thanks to Sigma's latest technologies, it's exceptionally lightweight and 30% more compact by volume than previous lenses of its type. Its low F-number equips photographers to shoot subjects at extremely close range, making this the perfect lens for travel, family photos, artistic compositions, and many other uses. It's a compact lens ideal for everyday use, offering uncompromising optical performance, functionality, quality, and elegance.
Sigma is organizing all its interchangeable lenses into three product lines; Contemporary, Art and Sports. Featuring the very latest technology, and combining optical performance with compactness, the Contemporary line covers a wide range of needs. Incorporating the very latest technology in these lenses, Sigma has solved the difficult problem of keeping size and weight low without compromising optical performance. The SIGMA 17-70mm F2.8-4 DC MACRO OS HSM is the first product from the Contemporary line. Featuring a wide zoom range, the lens has a focal range equivalent to 25.5-105mm on a 35mm lens.
This lens' minimum focusing distance is 22cm and the maximum magnification ratio is 1:2.8. At 70mm, the working distance becomes 5.52cm. When it comes to telephoto, it can shoot pictures with a similar sensation to a macro lens. Also, without the need to change the lens, it enables photographers to take a close up pictures of subjects such as jewelry and flowers. In order to secure a clear field of view, the design of this lens is very thorough, even down to the precise position of the engraved letters on the lens.
For a which is used lens used in everyday situations, the small size makes a big difference. By incorporating a smaller OS unit and optimizing the structure and power distribution of optical elements, the lens barrel has now become more compact. In order to ensure high accuracy of the product, the new compound material TSC (Thermally Stable Composite), which has high affinity to metal parts, is introduced for the lens barrel. It results in better durability of the parts and smaller zoom rings and scale rings. The dimension of this lens is 30% smaller than our conventional models.
This lens incorporates 2 FLD (“F” Low Dispersion) glass elements, which have performance equal to fluorite, 1 SLD (Special Low Dispersion) glass element and 3 aspherical glass lenses including double sided aspherical lens. By optimizing the power alignment of the lens, both chromatic aberration of magnification and axial chromatic aberration have been corrected. From infinity to macro, it achieves superior image quality through entire zoom range. This lens offers extraordinary expressive power and is capable of surpassing the requirement of the rigorous checking process of our new MTF measuring system “A1”.
The aperture value is F2.8 at the wide end (17mm), and is F4 at the telephoto end (70mm). The bright viewfinder aids focusing and composition of images. The fast apertures also offer useful functions such as fast shutter speeds to prevent an object from being blurred and ensuring a smooth bokeh in the background.
Sigma's own unique OS (Optical Stabilizer) function is incorporated. It offers effective correction of approximately 4 stops, which makes it possible to compensate for camera shake even in macro range photography where a small blur can be easily identified.
*1. The closer the lens is to the object, the less effective the OS function is.
*2. For Sony and Pentax, OS function is not incorporated.
Flare and ghosting conscious design
In order to achieve high rendering on this flagship lens, flare and ghosting were thoroughly measured from an early stage to establish an optical design which is resistant to strong incident light such as backlight. The Super Multi-Layer Coating reduces flare and ghosting and provides sharp and high contrast images even in backlit conditions.
The 7 blade-rounded diaphragm creates an attractive blur to the out-of-focus areas of the image.
This lens incorporates brass made bayonet mount which has both high accuracy and solidity, same as the mount for camera body. The special treatment to reinforce the strength is applied on the surface to make it a high quality lens that is resistant for long-term use.
Ease of use
The new product lines incorporate rubber for the attachment part of the provided lens hood. For better usability, the design of the lens cap and AF / MF changeover switch has been improved.
Based on these new lines, we have developed special software (SIGMA Optimization Pro) that can update the lens firmware and adjust parameters such as focus.
Evaluation with Sigma's own MTF measuring system “A1”
We used to measure lens performance with MTF measuring system using conventional sensors. However, we fve now developed our own proprietary MTF (modulation transfer function) measuring system (A1) using 46-megapixel Foveon direct image sensors. Even previously undetectable high-frequency details are now within the scope of our quality control inspections.
The SIGMA 17-70mm F2.8-4 DC MACRO OS HSM will all be checked using this “A1” before they are shipped.
All Sigma's manufacturing - right down to molds and parts - is carried out under an integrated production system, entirely in Japan. We are now one of the very few manufacturers whose products are solely “made in Japan”. We like to think our products are somehow imbued with the essence of our homeland, blessed as it is with clean air and water, and focused, hard-working people. We pride ourselves on the authentic quality of Sigma products, born of a marriage between highly attuned expertise and intelligent, advanced technology. Our sophisticated products have satisfied professionals and lovers of photography all over the world, because our manufacturing is based on genuine craftsmanship, underpinned by the passion and pride of our experts.
|Lens Type||Pentax K AF|
|Focal Length||17-70mm (35mm Equivalent = 25-105mm)|
|Maximum Aperture||f2.8 - 4|
|Dimensions||79 x 82.0mm (WxL)|