World's First Fisheye Lens for Crop Sensor Cameras

Sigma has announced yesterday that they are releasing the world's first 180 degree circular fisheye lens designed specifically for APS-C size digital SLRs. The Sigma 4.5 mm lens will feature a maximum aperture of f/2.8 with an HSM (hypersonic motor) mechanism for quiet zooming.
Other features of this lens include:

• Minimum focusing distance of only 5.3 inches (13.5 centimeters)
• Maximum magnification of 1:6
• Special Low Dispersion (SLD) glass to minimize aberration
• Availability for Canon, Nikon, and Sigma SLR cameras

The lens consists of 9 groups in 13 elements, with a total of six blades. Its weight will be 470g (16.6 oz). Pending field tests, this lens looks like it might be a welcome addition to those photographers with APS-C (cropped) sensor cameras. Pricing and availability is yet to be announced.