Leica Vintage Focusing Helicoid for Visoflex
I pick up interesting helicoid. It is for the macro to a reproduction ratio 1:1 and above.
Helicoid has a M42 mount, and thus is suitable for cameras of that system. I used it for Nikon D3100 through the M42-Nikon adapter.
Design and material helicoid says that it released to the 1930-40s. It has a brass body in the form of a tube, for the lens screw is M39. The inner part of the tube well is blackened. Side on the outside and have a distance scale DOF.
Leica helicoid in the extended state
Leica helicoid in the compact state
The helicoid rotates 360 degrees, while it increases the length of 2 cm. Proceedings smooth rotation.
Such a tool could be useful for those who are seriously engaged in macro photography.
Reproduction Ratio Test
For fun, I decided to try a macro reproduction ratio can be achieved at the APS-C camera with a crop factor of 1.5.
Found at analyzing processes with Industar-96U-1 3,5/50 enlarger lens (the only one that I had to screw M39), and tried to make test photos.
I apologize for the picture quality, lens low contrast and flare in the middle of the frame, but the idea of the reproduction ratio is clear.
For me is not useful for macro photography, since such a scale is rarely used. Usually, I manage extension rings and get a smaller reproduction ratio, which is suitable for many tasks when taking pictures of jewelry etc.
But I found it a different application. It's long and constructive allow using it to mount and focusing large format lenses on the digital camera. For this view, its helicoid perfect for me.
Also for mount lenses larger format, there is larger helicoid.
The mysterious helicoid is a part of Visoflex 1 or PLOOT accessories the pre-war version.