The Sigma 24-70mm f3.5-5.6 HF is one of several innovative products introduced by Sigma in 2001. This lens covers focal lengths from 24mm super-wide-angle to medium telephoto.
It employs a Helical Focusing system (HF) for focus adjustment, which allows for straight movement of the front lens elements.
Without the front lens element rotation, it allows for the use of a perfect hood and the easy use of polarizing filters.
Minimum focusing distance from the film plane to subject at all focal lengths is 15.7inch (40cm). The Sigma 24-70mm f3.5-5.6 HF incorporates an aspherical lens to minimize distortion, spherical aberration and astigmatism, resulting in high image contrast and resolution.
The lens also features a depth of field scale that serves for determining the subject's depth of field at a specific focal length and distance.
The lens materials used in this new lens are lead and arsenic free ecological glass.
