Sigma have announced two interesting new lenses designed for APS-C (cropped sensor) DSLRs like the EOS 40D and Rebel XTi.
The first is a Sigma 4.5mm f2.8 circular fisheye. This produces a circular image in the middle of the frame with a 180 degree view all around. If you lay the camera on it's back, you get a view of the whole sky with the horizon running around the edge of the circle!
The second lens is a Sigma 10mm f2.8 diagonal fisheye. This lens fills the whole frame, with a 180 degree diagonal field of view for the Nikon 1.5x sensor and 167 degrees for the Canon 1.6x sensor.
Price and availability are unknown at this point, though I have seen one rumor that the 4.5mm lens will sell for the equivalent of around $1000 in Japan. This may or may not be true and may or may not reflect the eventual price in the US!
Currently the only fisheye lens designed for Nikon and Canon APS-C sensor DSLRs is the Tokina 10-17mm fisheye zoom which is available in both Nikon and Canon lensmounts.
Here are the press releases from Sigma:
4.5mm F2.8 EX DC CIRCULAR FISHEYE
The Sigma Corporation is pleased to announce the launch of the new 4.5mm F2.8 EX DC CIRCULAR FISHEYE HSM lens. This autofocus circular fisheye lens has an angle of view of 180 degrees in all directions. It is exclusively designed for digital SLR cameras with the APS-C size image sensor. When used in conjunction with digital SLRs with APS-C size image sensors, it produces circular image within the frame. The F2.8 large aperture value produces a bright image in the viewfinder and allows photographers to take pictures in low light conditions, making it an ideal lens for Astrophotography and Aurora photography. Due to the quantifiable angle/area relationship it produces, this lens can be used for scientific and arts applications such as solid angle measurements of cloud distribution over the sky or vegetation distribution of the forest. The minimum focusing distance of 13.5cm/5.3inch and maximum magnification of 1:6 make it particularly useful for close-up photography. SLD(Special Low Dispersion)glass provides effective compensation of chromatic aberration. Sigma’s Super Multi-Layer Coating minimizes flare and ghosting. It is equipped with an inner focusing system that creates high definition and good image quality over the whole frame. The HSM (Hyper Sonic Motor)ensures fast and quiet autofocusing and allows full-time manual focus override by rotation of the focus ring.
10mm F2.8 EX DC FISHEYE HSM
The Sigma Corporation is pleased to announce the launch of the new 10mm F2.8 EX DC FISHEYE HSM lens. This autofocus fisheye lens is designed for use with digital SLR cameras equipped with APS-C size image sensors. The Nikon version produces a diagonal angle of view of 180°(154°for Sigma, 167°for Canon). The diagonal field of view of this fisheye lens produces striking images with exaggerated perspective and distortion. The minimum focusing distance of 13.5cm/5.3inch, and maximum magnification 1:3.3 allows subjects to be as close as 1.8cm/0.7inch from the lens’ front element. This close focusing capability allows close-up photography and also it is possible to make use of large depth of field that covers wide range of subjects. The Integral hood blocks out extraneous light and the Super Multi-Layer Coating minimizes flare and ghosting, creating superior image quality. The HSM(Hyper Sonic Motor)ensures fast and quiet autofocusing and allows full-time manual focus override by rotation of the focus ring. This lens is supplied with a gelatin filter holder at the rear, allowing the use of gelatin filters.