Equivalent focal length: 25-105 mm
Angle of view: 79.7 - 22.9°
Diameter: 79 mm
Max. magnification: 1:2.8
Working distance: 55 mm (focal length - 70 mm)
HSM is evidently NON-ring-type!
Brass bayonet mount
Price: $ 500
The Sigma C 17-70mm F2.8-4 DC MacroOS HSM is a standard zoom lens for digital SLR APS-C cameras. This is the first lens in Sigma's new-concept 'Contemporary' series.
It should not be confused with the identically-named lens released in 2010. This new lens is slightly smaller and lighter. It features a revised optical formula and new design marked ©.
The optical scheme comprises 16 elements in 14 groups, including three aspherical elements (including biconvex), one SLD and two FLD elements (with optical properties close to fluorite). Super multicoating reduces flare and ghosting, and provides sharp and high-contrast images even in backlit conditions.
The lens is equipped with an optical stabilizer claiming a 4-stop benefit. The OS efficiency decreases when used in macro mode. OS is not available for the Sony and Pentax mount.
It is the first time when Sigma has preferred Thermally Stable Composite, which is exceptionally hard and less prone to thermal contraction, to regular polycarbonate for its new lens series. TSC has similar thermal expansion to aluminum. As compared to regular polycarbonate, containing 20 or 30% of glass, TSC is meant to have approximately 70 or 25%. Correspondingly, it is 25% more flexible and resilient than polycarbonate.
USB Dock Station+ Sigma Optimization PRO Software is available for updating the lens firmware and adjusting its parameters (including focus).
LH780-03 petal hood included
Links to online resources:
Posted by: fiy94yan Date of publication: 18.09.2012