Sigma 70-200mm f/2.8 EX DG APO Macro HSM II
I'd heard good things about this lens, but the copy of this Sigma zoom I had for testing on a Nikon FX-body did not come across as a great performer.
It was soft over the entire frame when I tried to use it wide open. This is bad news for a lens whose main attraction is its constant f/2.8 maximum aperture. I had to stop it down around two full stops to f/5.6 for acceptable sharpness. Its sweet spot was between f/8 and f/11. My sample also suffered from a bad case of CA.
I returned it (and ended up buying a used Nikon 80-200 mm f/2.8 for about the same price as a new Sigma).
On a more positive note: Distortions were low. At the wide end there is just a hint of barrel distortions, changing to barely noticable pincushion distortions at the long end of the zoom range. Vignetting is noticable, but acceptable at FX, and negligible, even at f/2.8 at DX.
Mechanically, this is a typical Sigma EX-lens: The ring-type motor is fast and accurate, and allows manual over-ride. The broad rubberized zoom and focus control rings operate smooth and well damped. The overall length of the lens does not change and the front element does not rotate during operation. It comes with removable tripod collar.
It may be that the lens I received was a bad sample. If you want to try this out, make sure you get it from a store with a good return policy.
Rating: Ed: 30, User: - (normalized, 0=useless, 50=average, 100=excellent).
Mounts: Canon EF, Four-Thirds, Nikon F, Sigma SD, Sony A.
Aperture range: f/2.8 to f/22.
Optical zoom: 2.9x.
Close focus distance (CFD): 100 cm / 3.28 ft (from sensor plane).
CFD magnification: 1:3.5 / 0.29X.
Focus: AF (built-in, ring-type).
Filter diameter: 77 mm.
L x D, W: 184 x 86 mm, 1370 g.
Approximate street price: USD 949 (new, w/o tax).
Sigma is a family owned manufacturer of photographic equipment founded in 1961 in Japan. The company's main business is to manufacture third party lenses. However they also produce third party flash units and, since 2002, their own line of DSLR and compact cameras. Sigma's digital cameras use a special sensor, developed by Foveon, that records full color information for every pixel. In late 2008 Sigma acquired Foveon.