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Review by Klaus Schroiff, published December 2005
Introduction
The Sigma AF 70-200mm f/2.8 EX DG HSM APO (here: Canon EOS mount) is one of Sigma's pro grade EX lenses.
Compared to the initial version of this lens the new DG (Digital Grade) variant features a new coating
optimized for the special reflection characteristics of today's images sensors.
Over the years Sigma has earned a good reputation with these lenses so they were and are a popular alternative
to the usual quite pricey genuine manufacturer zooms in this range.
On APS-C cameras its field-of-view resembles a classic 112-320mm lens
on full-frame cameras. As a full-frame lens it remains usable on all kinds of SLRs naturally. The 70-200mm f/2.8 EX is
available for all SLR systems except four-thirds.
By standards of most mortals the Sigma is big and heavy lens with a dimension of 86x184mm and a weight of 1270g.
Adding the (included) flower-shaped hood increases the length even further (see above). That said this data remains in-line
with similar large aperture products by the genuine manufacturers. Besides the hood the lens also features a detachable
tripod mount which certainly makes sense on a tripod regarding the weight of the lens.
The optical design is made of 17 elements in 14 groups, including 4 SLD elements (two big ones in the front group).
The min. focus distance is 1.80m resulting is a max. object magnification of 1:7.8 at 200mm. The lens features 9 aperture
blades. The filter size is 77mm.
The mechanical quality of the 70-200mm f/2.8 EX is impressive indeed - a true pro grade lens. The outer
barrel is made of first class materials with the typical EX crinkle finish. The zoom ring is very well damped
whereas the focus ring feels a little too smooth. The HSM drive, Sigma's ultrasonic AF drive variant, is very
fast and provides full time manual focus control. Please note that the HSM drive is only available for Sigma, Canon
and Nikon mounts. Minolta and Pentax users have to live with a standard micro motor which is surely somewhat slower.
The lens does not extend during zooming and the front element remains in place so using a polarizer is no problem
unless you attach the deep hood.
It is possible to use both Sigma tele converters transforming the lens either in a 98-280mm f/4 (w/1.4x EX) or
140-400mm f/5.6 (w/2x EX) combination.
It is worth to mentioned that I tested the non-DG variant earlier this year but this sample suffered from
a rather extreme centering issues. Even worse Sigma was unable to repair the problem.
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