Sigma are showing the 24-135mm f/2.8-4.5 zoom lens to PMA 2003.The 24mm
wide-angle gives more than 80 coverage and ranges up to a useful 135mm
telephoto setting with its angle of 18.2. One Special Low Dispersion
(SLD) glass element and two Aspherical Lenses effectively compensate the
colour aberration, as well as astigmatism, results in a high level of optical
performance. At 24mm focal length this lens has a fast f/2.8 maximum aperture.
The lens incorporates an internal focusing system, which eliminates front
lens rotation, allowing easier use of polarizing and graduated filters or
petal type hoods. The lens materials used in this new lens are lead and
arsenic free ecological glass.