Helical Focus Mount For Focus Stacking With Carl Zeiss Jena 35mm f/2.8 Lens

I had this Zeiss-Jena Zebra (black and chrome) lens with back end missing - no mount on the lens.

And I have some 2x macro converters. These are perfect focus helicoids for DIY work!
20mm way of focus is good for many shorter focal lengths. For example I already made an focus mount for a Som Berthiot projection lens with focal length 75mm with such a teleconverter.

Here the macro teleconverter: Take the screws from the camera side mount away, and you get the mount + optics.

The lens assembly is screwed into the back mount. And the thread is additional glued together. In this case I have to apply extreme force to open it. Next time I will try heat.

In this case I took the mount on the lens away too. Now I get enough place to fit the lens front inside this.

Here you see the manual Zeiss wideangle lens without mount and iris ring:

I have taken the rest of the back end of the lens away, and the front zebra focus ring

With a small turning lathe I machined the focus ring as a kind of hood for the lens.

Not shown in pictures is next step: Out of an old single lens reflex camera I took the 1/4" tripod hole base. This part has three screw holes. I filed the bottom side of the hood ring flat. There I copied the hole position. And not I tapped small threads. Now I could screw the tripod base onto the hood ring. The hood ring itself is at the moment glued to the lens front.

The special feature of this setup is the fixed front lens position while focussing!
This should result in more easily stackable images - but I am not sure if modern stacking programs need such a fixed lens position.

Here the result: I do not gurantee that the front mount never break. But on a photo tour I had the camera on this lens mounted, and the lens on the tripod. And I carried the tripod - with no problem.

Here some first results with this stacking optimized lens:

Glas corrosion on an old Zeiss Tessar lens and right side a Zeiss Contax IIa Color Dial with Cine Release (I would know the the name Autoknips, but I think that is a different manufacturer)

glass corrosion