Omnar Releases Modern Interpretation of Classic 1934 Bertele Lens
British company Omnar Lenses has announced the Omnar Bertele 5cm f/2 MC FLB, a modern version of the 1934 5cm f/2 Jena lens designed by Dr. Ludwig Bertele. The new lens is the product of a five-year development process led by Hamish Gill, known for the photography website 35mmc.com, and Chris Andreyo of Skyllaney Opto-Mechanics, a company specializing in the custom construction and repair of Leica M-mount lenses.
The original 1930s Jena lens is regarded for its distinct optical rendering but is also known to exhibit multiple limitations when used on modern equipment. These include degraded coatings, soft and scratch-prone glass, and focus shift—particularly at medium apertures and close distances. The current version, manufactured entirely in the UK, is designed to maintain the original six-element, three-group Sonnar formula while addressing those technical issues through new engineering approaches.
To solve the long-standing focus shift problem, Omnar Lenses developed a proprietary Floating Lens Block (FLB) system. This mechanism counteracts changes in effective focal length caused by aperture adjustments, a known flaw in the original Jena design. Traditional solutions, such as the ninja-star shaped aperture blades used in post-war Oberkochen variants, mitigated the focus shift but at the expense of out-of-focus image quality. By contrast, the FLB system allows Omnar to retain circular aperture blades, preserving the lens’s original bokeh characteristics while stabilizing the focal plane across the full aperture range from f/2 to f/22.
According to the designers, the FLB mechanism is able to maintain focal accuracy with rangefinder focusing systems, even during close-up shooting—a scenario in which the original design typically failed. This was achieved by incorporating a non-linear RF cam profile that translates the historical 52.4mm effective focal length of the original design to the modern 51.6mm standard used by contemporary M-mount cameras.
Despite the mechanical and optical upgrades, the core optical layout remains unmodified. The glass elements are fabricated using modern materials that preserve the multi-coating aesthetic of later Bertele variants while eliminating historical weaknesses such as air bubbles and surface softness. The lens also features a large 62mm image circle, enabling coverage of medium-format sensors like those found in the Fujifilm GFX and Hasselblad XCD systems.
The FLB system has been made open source, and Omnar has published technical documentation for other lens designers to reference. This approach has been much appreciated by manufacturers and creators worldwide as a significant advancement in rangefinder lens design, comparable to the adoption of aspherical and floating element technologies in previous decades.
Here are some sample pictures, from Omnar Lenses’ website:
The Omnar Bertele 5cm f/2 MC FLB is constructed with a machined brass housing and assembled by hand. It is designed exclusively for Leica M-mount and is available in a limited production run of 30 units. Preorders are open at a price of £2,750 (approximately $3,717), with shipping scheduled for September 2025. Additional production batches are planned for 2026.
