(From Sigma lens literature) C | Contemporary: 17-70mm F2.8-4 DC Macro OS HSM.
Mainly used for general-purpose photography, this everyday lens covers a range equivalent to 25.5-105mm on a 35mm camera. A large-aperture lens that opens up to F2.8, it’s surprisingly compact in size. Great for treasured snapshots of travel or family occasions, it a lso handles shots that are a little bit more creative. Designed to be the kind of lens you carry around with you all the time, it delivers simplicity and is so user-friendly that’s sure to satisfy even the most demanding of users.
Features
1. Excellent for macro photography
This lens has the minimum focusing distance of 22cm throughout the entire zoom range and a m aximum magnification ratio of 1:2.9. The size and framing can be adjusted by rotating the zoom ring, making macro photography easier than using a fixed focal macro lens. For further convenience, the maximum magnification ratio at each focusing distance appears on the side of the lens barrel.
2. Optical Stabilizer (OS)
Sigma’s own unique OS (Optical Stabilizer) function is incorporated. It offers effective correction of approximately 4 stops, which makes it possible to compensate camera shake even in macro range photography where a small blur can be easily identified.
3. Superior optical performance
FLD (“F” Low Dispersion) glass, that has a performance equal to fluorite, and SLD (Special Low Dispersion) glass are used for maximum correction of chromatic aberration. Three aspherical lenses, including a double-sided aspherical lens together with the latest design, prevent and correct all types of aberrations including astigmatism, achieving high quality images throughout the entire zoom range.
4. New material TSC (Thermally Stable Composite)
The new material “TSC (Thermally Stable Composite)”, which has little contractility especially in temperature changes, as well as maintaining firmness, is incorporated into the lens barrel. Compared to Polycarbonate which is generally used, TSC has higher elasticity by approximately 25%. Since thermal shrinkage is low, it has high affinity to metal parts which contributes to high quality product manufacturing. It also allows other parts such as the zoom ring and scaling to be smaller.
5. Flare and ghosting conscious design
From an early stage, flare and ghosting are thoroughly measured to establish the design which is resistant to strong incident light such as backlight. Sigma’s Super Multi-Layer Coating reduces flare and ghosting, and provides high contrast images even in backlit conditions. The supplied petal-type hood can be attached to block out extraneous light which has a harmful influence on the rendering of the lens and prevents internal reflections.
6. Brass made bayonet mount
This lens incorporates a brass made bayonet mount which has both high accuracy and durability. The special treatment to reinforce its strength is applied to the surface to make it a high quality lens that will easily withstand long-term use.
