Open Sonnar v2.0 - Focus Adapter for Zeiss 50mm

One of the most beautiful features of digital fabrication is the way it allows us to salvage the past. Our reality may be the life's work of millions of brilliant people, but often, time and technology relegate their artifacts to novelties or footnotes. Sometimes, though, for a low cost and a modest amount of design time, 3D printing enables us to rip their work into the present, to compete with modern day on its own merits. The Carl Zeiss Sonnar 50mm 1:1.5  is one of these objects worth reviving.


The lens was made in the early 1930's, from robust metal and optically flawless glass in a Sonnar arrangement - a designation describing the number and placement of glass elements that focus the light, and also an arrangement known for its sharp-but-painterly image quality. Unlike modern lenses, however, it was designed to be used on a camera with the focusing mechanism built into the camera body, and not the lens - which means that adapting it to a mirrorless digital camera required expensive and obscure adapters.

Provided here is a 3D-printable integration between this lens and a modern camera. It cleanly adapts to Sony NEX / Alpha / E-Mount cameras.

It is a single-helicoid focusing mechanism, which means the lens rotates as it focuses. The focus range is roughly 30cm to slightly past infinity.



Some assembly is required! Cleaning the parts before using is critical, or dust will definitely end up on your sensor. Using a plastic compatible grease on the helicoid before assembling greatly enhances usability. Super Lube or similar works well. The body of the lens snap-fits in to the inner helicoid portion of the adapter with a decent but safe amount of force. The two halves of the adapter need to be twisted together. Looking at the adapter from the inside, align the dot on the inside of the inner helicoid to the bar on the inside of the outer helicoid, as shown in the last photo here. Then twist the helicoids together until you feel the assembly lock *click* in to place.