The Sigma 4.5mm f/2.8 EX DC HSM Lens is a spherical fisheye lens that easily captures a full 180° view in all directions, in a circular image. Even the most familiar and mundane of subjects can be portrayed with startlingly fresh new expressions through exaggerated perspectives and unusual distortion effects. It is well suited for academic and technical measurements such as solid angle measurements, cloud cover measurements & virtual reality.
Having the HSM (Hyper Sonic Motor) incorporated into this lens allows for focusing to be quieter and more responsive. In addition, the HSM feature gives this lens the capability to auto focus with all Nikon DSLR cameras (including the D40 and D40x). This lens provides the equivalent focal range of approx. 6.75mm when used with a Nikon digital SLR camera (*).
DC lenses are exclusively designed for digital SLR cameras. The image circle (rear of lens) is made to match the smaller dimensions used for the image sensor on digital cameras. As a result these lenses are also more compact and lightweight, and are better matched to digital SLR cameras.
Note! (*) Not compatible with 35mm cameras or digital cameras using full-size image sensors (e.g. D3, Kodak DCS14n or DCS PRO SLR/n).