Test made by Jakob Norstedt-Moberg, Fotoverkstan, November 19, 2005
The Nikkor 10.5mm Fisheye is a highly appreciated lens for capturing spherical panoramas. It is intended for use on cameras with DX size sensor, i.e. Nikon D70 or D2X, but can be mounted on a full frame camera as well. The problem is the lens hood, which is fixed and prevents a large image circle. Some brave people dare carving it off with a knife.

I still have the hood on the lens, but I got curious about which field of view the lens is able to give at its best.

This simple setup show that the field of view under some circumstances is more than 180 degrees.

Image 1. This is a simple setup. Notice the pins with ball heads at the left corner (arrow)

Image 2. This is the same setup from above. Notice that the pins are behind the golden ring of the lens, no doubt.

Image 3. This is the image captured by the camera, a full frame Kodak SLR/n. The lens is focused at 0.4m, F=5.6. You can see a small pin with a ball head in the top right corner. (The odd black masking is due to the lens hood, which can not be removed without violence.)

Image 4. This is a 100% crop of the top right corner, corrected for chromatic aberration. Notice the two pins, which are clearly visible. They are couple of centimeters behind the front lens of the fisheye, thus it has a field of view larger than 180 degrees.

Addendum
January 6, 2007 Since doing this test in 2005, I have cut off the sun hood of the lens to allow full use on full-frame cameras like my Kodak. It is a thrilling experience, but well worth the effort since it makes it possible to stich a 360 degrees panorama of high quality from just two images:

Source image 1

Source image 2

Resulting panorama