Sigma 14mm f/2.8 EX HSM
As seems to be with norm with Sigma, quality control seems to be an issue. I have seen some good reports about the sharpness on this lens, and also some bad.
For what it is worth: The sample I tried (I borrowed it for trying out and ended up not buying) was not a great performer. On FX, the corners was blurred (not just soft) on all apertures. Even the centre was noticable softer than both Nikon's and Canon's 14 mm f/2.8 offerings. Stopping down to its optimum aperture (f/8) helped, but the image was still not really sharp. It also flared easily. On the good side, it had very low distorttions, and the build quality was excellent.
If you want to buy this, make sure you check out the exact sample you are going to buy carefully, to avoid ending up with a dud. Even if you get it dirt cheap a blurry lens is no joy to use.
The Pentax and Sony versions of this lens is without the built-in focus motor.
Rating: Ed: 20, User: - (normalized, 0=useless, 50=average, 100=excellent).
Mounts: Canon EF, Nikon F, Pentax K, Sigma SD, Sony A.
Aperture range: f/2.8 to f/22.
Close focus distance (CFD): 18 cm / 0.59 ft (from sensor plane).
CFD magnification: 1:5 / 0.2X.
Focus: AF (built-in, ring-type).
Filter: gel insert (rear).
L x D, W: 82 x 91 mm, 630 g.
Approximate street price: USD 800 (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.