Enter the elusive 58mm 1.5 Sonnar lens in Leica screw mount.
Every now and then you see them for sale on auction sites. The ever returning question is, are they real, or are they Russian fakes? I have a theory on their history…
I am a happy owner of the Zeiss Serial numbers book by mr. Thiele. It lists a score of 58mm 1.5 Sonnar lenses, but none of those are listed as Leica Thread Mount, also known as M39 in the book. But, the list of serial numbers in the book has been corrected several times throughout the years and has up to this day been disputed by a few other sources. Seems the Carl Zeiss record keepers were human after all!? So, can the list be at fault and is there a never-listed batch of 58mm 1.5 Sonnar lenses in Leica Thread Mount, that seeps through and surfaces on those online auction sites and with dealers?
I highly doubt it. There is no historical evidence for those lenses being either real or fake, but there is a technical reason why this tale might be a myth.
The rangefinder cam travel in the Leica (both screw mount and bayonet mount cameras) is designed to match the true focal length of the Leica lenses: 51.6mm. This is known as the Leica Standard. The Zeiss Contax Standard is close, but not the same, it’s 52.5mm. After the war, the Russians confiscated the Jena plant, its supplies and machinery and even a great part of the German workers and re-located them to Charkov, Ukraine. The confiscation was considered damage repairs for the thriving FED factories in Charkov, that were destroyed by the German armies during their offensive against the Russians. As a result, Russian lenses are made to the Contax Standard, which is why some folks claim the lenses cannot focus correctly on a Leica. In fact, Russian 50mm lenses (which in fact are 52.5mm) can just about be adjusted to focus correctly, but that's a whole different story, that I will be writing a post about soon! Any Russian lens with a focal length other than ~50mm cannot be adjusted for correct focusing on a Leica. And while a 52.5mm lens can sort of wing it to the Leica Standard, a 58mm lens would be a whole different story.
For an 58mm lens to focus correctly on a Leica, it will need to have a specially-made helix that adjusts for the Leica Standard. If it doesn't, it will never focus correctly over the entire focus distance, but focus will 'drift' when focused either near or far. Whenever the lens is optimised for either near or far, the other end will drift as the lens gradually ‘gets out of sync’ more with the rangefinder assembly as it moves through the focus distance.
I used to own a few Carl Zeiss Jena Sonnar 50mm 1.5 lenses from the wartime era. They were confirmed to be original Carl Zeiss and were focusing accurately throughout the whole focus range on a screw mount Leica! Which means that Zeiss likely had a way of creating Leica Standard barrels for their Sonnar lens optical units. But, I highly doubt Zeiss took the effort to create a Leica Standard adjusting helix for a 58mm lens... That would have been a design that was expensive to manufacture, I suppose. Especially given the small amount of those lenses that apparently exists.
My GUESS is the optical units in these lenses were Carl Zeiss (and designed for another lens mount), but the Leica mount lens barrels were not. They may have been created by Zeiss employees who decided to make a buck on the side, after the war ended there was money to be made on the black market. They may even have been made secretly in the Zeiss factory, but I highly doubt they were a Zeiss design.
I have never seen the insides of a 58mm lens or test shots of an untampered-with 58mm lens over the full focusing distance, a Leica Standard adjusting helix would be a dead give-away of it being Zeiss-designed…