This strange little device has been a godsend to a number of photographers who have been fortunate enough to find a bargain in a high quality, professional roll film or large format camera when searching around the for sale columns or in junk shops.
Such cameras have traditionally been designed for large, professional tripods which have a bigger than normal mounting screw (9.5mm, 3/8”) attached to them. While current professional tripods and heads can offer this fitting as an option, these are very expensive and more often than not the photographer already has a tripod. This little adapter allows the larger socket (9.5mm, 3/8”) to be mounted onto more traditional tripods that are available today and use the smaller (6.4mm, ¼”) thread.
NOTE: This adapter is also useful for when using a professional ball head on a regular tripod or monopod. Insert/screw this into the base 3/8 inch ball head and then you can mount onto a tripod or monopod that uses a regular 1/4 inch screw. A 1/4 inch screw is the type that fits into 99% of cameras like Canon, Nikon, Pentax, Minolta, Olympus, etc.
By simply screwing the adapter firmly into the tripod mounting socket on the base of the camera, the photographer can now mount it onto his existing tripod in the normal way. There is no need to buy a new tripod for that special camera, simply adapt the mount with one of these little steel rings and off you go.