This Kenko wide-angle adapter lens has a 37mm thread to
fit many video cameras. In the image above it is mounted on the TR7000, a
first-generation Digital 8 camera. It makes your lens focal length
0.42 as long, giving you a very wide-angle view with some barrel distortion
(not a true "fisheye", but close). I tried it on two Sony Digital 8 cameras:
a TR7000 and a TRV720, and both showed vignetting (dark corners) at full
wide setting. Both these cameras use 1/4" imaging chips. I believe
that many of the newer cameras use 1/6" chips and given the smaller chip
size, might not show the vignetting with this lens, but I haven't tried it.
The lens is designed for fully-wide use, and if you zoom in the image will
become softer and smeared. I took the images below while standing in the
same place, and zooming in from fully wide angle. Both these cameras
have 25x optical zoom: I only zoomed in about 2/3 of the way. You can
go further but the image becomes even more smeared.