Funleader, together with Mr. Ding, announced a new Contax G28 lens-to-Leica M-mount conversion project. This project began in 2019 with the G35 and continued with the G45, with the goal of allowing classic Contax G lenses to be used on Leica M-mount cameras without permanently modifying the original lenses. The newly announced G28 conversion features a brass internal structure for durability and an aluminum exterior to reduce weight, completing a three-lens lineup that covers 28mm, 35mm, and 45mm.
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Full details on the new lens after the break:
Lens features:
Additional information:
Contax G series, launched in the 1990s, stands as one of the few rangefinder systems to achieve autofocus while maintaining traditional rangefinder handling. Developed jointly by Contax and Carl Zeiss, the system featured a lineup of premium T* coated lenses. Among these, the 28mm, 35mm, and 45mm focal lengths have become the most beloved by rangefinder enthusiasts worldwide.
The G28 features a Biogon symmetrical optical design with 7 elements in 5 groups, providing a 75° wide-angle field of view. With a maximum aperture of f/2.8, minimum aperture of f/22, closest focusing distance of 0.5m, 46mm filter thread, and weighing just 150g, this lens exemplifies compact precision.
What sets the G28 apart is its remarkable barrel distortion control—a mere 0.3%, virtually negligible for a wide-angle lens. MTF charts reveal that at f/2.8, the G28’s center resolution already surpasses the legendary G45 (often hailed as the “world’s best standard lens”), with optimal performance around f/5.6 and remarkably consistent edge-to-edge sharpness.
In terms of rendering, the G28 delivers crisp, contrasty images with vivid color reproduction, particularly excelling with red tones and blues in low-light conditions—the signature Zeiss look. Even the bokeh from this wide-angle lens proves surprisingly pleasing and smooth.
Technical Notes
The G28 Leica M Conversion Kit follows the proven non-destructive conversion approach of its predecessors. Using the dedicated Conversion Helicoid, users with basic practical skills can achieve rangefinder-coupled focusing virtually indistinguishable from native Leica lenses—smooth focus travel, precise aperture damping, and seamless body integration.
Compatibility & notes:
Press release:
The project aims to bring classic Contax G lenses, originally designed for the Contax G autofocus rangefinder system of the 1990s, to modern Leica M cameras without permanently modifying the original lenses.
A Classic System
The Contax G system, developed by Contax and Carl Zeiss, debuted in the mid-1990s and included several well known lenses such as the Planar 35mm f/2, Planar 45mm f/2, and Biogon 28mm f/2.8. While the cameras themselves have long been discontinued, the lenses remain popular among photographers for their distinctive rendering and strong optical performance. Many photographers who own these lenses also use Leica M cameras, which has led to ongoing interest in adapting the lenses to the Leica M mount.
A Non-Destructive Approach
Rather than permanently altering the optics or original mount, the conversion kits are designed to be installed without modifying the lens itself. The optical elements and original Contax G mount remain intact.
Development Timeline
The project began in 2019 with the release of the G35 conversion kit, which adapted the Planar 35mm f/2 for Leica M cameras. While the first version proved popular and sold out quickly, the team continued refining the design. In 2021, the G45 conversion was introduced for the Planar 45mm f/2. Improvements included smoother focus damping and refinements to the internal mechanical structure. These updates later informed the release of G35 v2.0 in 2025, which featured a redesigned focusing mechanism and improved internal construction based on user feedback. The series now concludes with the G28 conversion, announced in 2026. Materials and Design For the G28 project, the team selected a combination of materials to balance durability and weight. The internal structure uses brass components for stability and longevity, while the outer housing is made from aluminum to keep the overall weight manageable.
Three Lenses for Everyday Photography
Together, the three converted lenses cover a practical focal range:
This range, from 28mm to 45mm, is commonly used for street, documentary, and travel photography.
Continuing the Exploration
With the release of the 28mm, 35mm, and 45mm conversion kits, Funleader and Mr. Ding mark a major
milestone in the Contax G conversion project. While these three lenses represent a key stage, the team
leaves open the possibility of developing conversions for other focal lengths in the future, continuing
their mission to bring classic lenses to modern camera systems and keep vintage optics alive in the
digital era.
Related videos:
The Contax Planar 35/2 T* lens v2.0 for Leica M-mount by Mr. Ding is now available in black
The Contax G45 f/2 lens for Leica M-mount by Funleader is back in stock (limited supply)
