The Sigma 17-70mm f/2.8-4 DC Macro HSM Lens for Pentax is a standard zoom lens designed especially for DSLRs with APS-C-sized image sensors. This lens has a 35mm-equivalent focal length range of 25.5-105mm, providing wide-angle to portrait-length angles of view for use in everyday shooting situations.
This lens features a fast f/2.8-4 maximum aperture to help better control your focus plane and to aid in low-light shooting. The Hyper Sonic AF Motor delivers fast, smooth, and quiet auto focusing that greatly benefits video applications. This AF motor can also be instantly deactivated by rotating the manual focus ring, giving you the ability to fine-tune your focus manually. The integration of two FLD, one SLD, and three aspherical lenses in the construction helps to reduce the effects of chromatic and chromatic axial aberrations, and Super Multi-Layer coated elements help to increase contrast for sharp, clear imagery.
As part of Sigma's new Contemporary line of lenses, this lens is designed using Thermally Stable Composite (TSC) materials to help reduce the overall weight and size of the lens barrel by about 30% without compromising on optical integrity, rigidity, or overall durability.
- Contemporary Lens Line
- This lens is the first lens produced as part of Sigma's Contemporary line; deeming it lightweight and compact while still exhibiting high optical performance. This lens' wide range of focal lengths makes is suitable for a variety of shooting applications. Utilizing an optimized distribution of optical and electronic elements, the size of the lens barrel is able to be reduced in size by approximately 30%. This reduction in weight is also afforded in part through the use of TSC materials in the barrel construction. This material offers high durability and rigidity but with less bulk than metal components.
- Macro Shooting Capabilities
- This lens features a maximum magnification of 1:2.8 and a minimum focus distance of 8.7" / 22cm, giving a working distance of just 2.2" / 5.5cm when shooting at the 70mm focal length.
- Optimized Lens Construction
- Two FLD (F Low Dispersion) glass elements, one SLD (Super Low Dispersion) glass element, and three aspherical glass elements, including a double-sided aspherical lens, are integrated into the lens' construction to help improve overall image quality. The combination of these elements provides a reduction in both chromatic and axial chromatic aberrations throughout the focusing and zoom ranges. A Super Multi-Layer Coating is also applied to lens surfaces to reduce the appearance of lens flare and ghosting, which helps to maintain image contrast and color fidelity when working in strong lighting conditions.
- Hyper Sonic AF Motor
- The HSM (Hyper Sonic Motor) provides fast, quiet, and smooth auto focusing that is well-suited for use with video applications. This AF motor can also be manually overridden at any time by rotating the focusing ring, giving you the ability to fine-tune image sharpness through manual focusing.
- Other Features
- A large maximum aperture of f/2.8-4 helps with low-light photography and also offers greater control over your focus plane for selective focus shooting.
- A brass bayonet mount provides reinforced durability at the connection point between the lens and your camera.