Some info I had saved on this lens. If you stand in front of the camera with the cable release, you can photograph from your toes to your nose.
Exposures are made by making part of the exposure with the wheel in front of the lens, and with a light puff of air from a rubber bulb at the end of a tube conected to the lens, like a barbers bulb, the wheel turns, just enough to move the fins a few degrees. Then the rest of the exposure is made with the wheel swung away from the ray path. Variations work too. All the exposure can be made with the wheel in the ray path, with the puff of air to move the fins, or the exposure can be made without the use of the wheel and that would make an image with greater exposure in the center than the edge by about three stops. That can be OK if using black and white film, and then you don't have to burn the edges down!
The important advantage with this lens is that the image is very wide angle, and big enough to hold the details, so for contact printing, silver, platinum or alternative, there is nothing like this.
Here is a link for anyone interested: [
www.cameraquest.com]